# Check Engine Light



## KMixson (May 15, 2017)

I have a problem with my car that I have never heard of anyone having with their car before and I am a mechanic. As I drive to work from my girlfriends house, when I get to a specific location the check engine light comes on. It has done it at that location every time the last 5 times I have come through there. It is a 2001 Toyota Avalon and the code it throws is P0440 which is "Evaporative Emission Control System Malfunction". It did it again on my to work this morning. Any other mechanics on here have any idea what it could be?


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## edwonbass (May 15, 2017)

Sometimes a loose or faulty gas cap can cause this code.


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## KMixson (May 15, 2017)

edwonbass said:


> Sometimes a loose or faulty gas cap can cause this code.



I know it can, but at the exact same spot in the road? It started on 3/20/17. Then again on 4/10/17, 4/27/17, 5/5/17 and now today. I can drive it all over town with no problems and it does it at this one spot as I go to work. I go this way when I need to go to the bank on my way to work.


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## Johnny (May 15, 2017)

.








I had a 1990 Corolla that had a VERY small crack in the gas cap
that made the CEL come on - my tire shop told me about it.
changed the cap - issue resolved.

.


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## lovedr79 (May 15, 2017)

replace the cap. it is probably coming on at the same spot due to the way the ECM works. it might take so many faults of that code before it sets triggers the CEL. you just happen to go the same way and it seems like a coincidence


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## KMixson (May 15, 2017)

I will change the cap.


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## onthewater102 (May 15, 2017)

Is it the same place or the same distance traveled from the start of your trip?

Same distance would mean roughly the same fuel consumption which would mean roughly the same change in pressure in the tank.


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## KMixson (May 15, 2017)

It is the same spot. The distance traveled varies between 50-400 miles. My boss asked me if there could be a meth lab in the area? I looked on Google maps and there is nothing there that stands out to me. There are two florist, a pottery barn and a gastroenterology site but they are all closed when I come through there at 4:15AM in the mornings. It has not happened to me as I have gone my main route.


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## KMixson (May 15, 2017)

I will probably be coming through there again Wednesday or Thursday morning and I will see if it does it again. I have a gas cap ordered and it is scheduled to get to my place Wednesday so I won't be replacing the old one until maybe Thursday. Next Monday morning will be the real test with the new cap.


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## onthewater102 (May 15, 2017)

Definitely alien activity then - only thing that explains it!

When you do figure it out please let us know.


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## Captain Ahab (May 15, 2017)

What color is the car? 

You need to stop right before you get to the spot in the road, get out of eh car, walk around the car counterclockwise three times and then sprinkle some water on the hood while chanting GAS CAP GAS CAP over and over.

Problem solved.


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## KMixson (May 15, 2017)

Captain Ahab said:


> What color is the car?
> 
> You need to stop right before you get to the spot in the road, get out of eh car, walk around the car counterclockwise three times and then sprinkle some water on the hood while chanting GAS CAP GAS CAP over and over.
> 
> Problem solved.



Then those nice young men in their clean white coats will take me away ho-ho hee-hee ha-haaa.


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## edwonbass (May 15, 2017)

Could also be a loose nut behind the wheel. :lol:


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## Captain Ahab (May 15, 2017)

Well - there are several solutions:

Are you left or right handed?


are you drinking coffee when this occurs


And

is the road up or down hill?


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## KMixson (May 16, 2017)

edwonbass said:


> Could also be a loose nut behind the wheel. :lol:




I have had this problem for ages. I am only interested in problems that I can actually fix now. :LOL2:


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## lovedr79 (May 21, 2017)

Any update?


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## Captain Ahab (May 21, 2017)

The aliens took him - he will be missed


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## LarryMc (May 21, 2017)




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## KMixson (May 21, 2017)

I will be going through that area Monday morning about 4:15 AM. That will be the test. I went through there traveling the opposite direction about 9:00 AM Saturday morning and the light did not come on. I do have a new Toyota OEM gas cap installed. I was planning on going through there Wednesday or Thursday morning but my job had a change of plans and I did not make it. I will post the results Monday morning.


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## Captain Ahab (May 21, 2017)

Captain Ahab said:


> The aliens took him - he will be missed




Wrong again - he is back i guess they released him. . . . . [-X


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## KMixson (May 21, 2017)

Captain Ahab said:


> Captain Ahab said:
> 
> 
> > The aliens took him - he will be missed
> ...



I guess I wasn't a keeper? :LOL2:


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## KMixson (May 22, 2017)

Well, It came back on in the same spot this morning on the way to work. I have noticed they are doing some paving on the road about a mile before I get to this spot. They only work at night and shut down during the day. Do you think my car could be sniffing hot asphalt in that area and just takes that long to register it for sensors? I do know the smell is real strong when I come through their construction zone.


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## lovedr79 (May 23, 2017)

KMixson said:


> Well, It came back on in the same spot this morning on the way to work. I have noticed they are doing some paving on the road about a mile before I get to this spot. They only work at night and shut down during the day. Do you think my car could be sniffing hot asphalt in that area and just takes that long to register it for sensors? I do know the smell is real strong when I come through their construction zone.



I am at a loss now. that is really odd. propane or natural gas lines around that area? this is really bizarre. the doesnt come on any other time?


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## KMixson (May 23, 2017)

That is the only place it comes on. It only comes on when I travel through there at 4:15 AM on Monday mornings. As I had said in an earlier post I went through there Saturday morning going the opposite way and it didn't come on. They have been working on the road about a mile before I get to that point. I do not know what exactly what they are doing but they could be dealing with a gas line. They have been working on it now for about three months. They only work on it at night from about 10PM to 6AM and then reopen all of the lanes for the morning rush. They tear up the asphalt at night and then lay it back down in the morning. When I go through there all I smell is asphalt. I have never seen a check engine light come on like this before.


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## GTS225 (May 23, 2017)

I suggest you have your local Oreilly's read the fault code. This should help narrow down what exactly is throwing the check engine fault. It might also push you/us in the right direction for diagnosis.

Roger


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## KMixson (May 24, 2017)

The code is P0440 which is "Evaporative Emission Control System Malfunction". I have read the code six times now. It has all that it shows. The most probable causes for this code is faulty/loose gas cap, EVAP canister, leaking vacuum hoses and fuel tank leak. I have replaced the gas cap. The part I don't understand is why is does it where it does it and nowhere else? It happens on the way to work from my girlfriends house at the same location every time. I didn't realize it until about the third time. I have a code reader that will read live data from the OBD II. My next step will be to connect it to the OBD II port before I drive through there again.


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## lovedr79 (May 24, 2017)

I am still baffled by this. LOL! my cousin has a forester, he was getting the same code. but it was all the time. his evap canister had crack...... wasnt cheap to replace. but in your case it is weird that it is one spot that triggers this. keep us posted.


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## Captain Ahab (May 24, 2017)

KMixson said:


> The code is P0440 which is "Evaporative Emission Control System Malfunction". I have read the code six times now. It has all that it shows. The most probable causes for this code is faulty/loose gas cap, EVAP canister, leaking vacuum hoses and fuel tank leak. I have replaced the gas cap. The part I don't understand is why is does it where it does it and nowhere else? It happens on the way to work from my girlfriends house at the same location every time. I didn't realize it until about the third time. I have a code reader that will read live data from the OBD II. My next step will be to connect it to the OBD II port before I drive through there again.




You need to brake (ort break) up with her - she might get to your boat next!


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## DaleH (May 24, 2017)

Is the route before that spot full of quick up & down hills? Big bumps? Or anything out of the ordinary that you don't encounter in your other travels?

Signal notes/synthesizer sequence to _Close Encounters of the 3rd Kind_ ...


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## KMixson (May 24, 2017)

DaleH said:


> Is the route before that spot full of quick up & down hills? Big bumps? Or anything out of the ordinary that you don't encounter in your other travels?
> 
> Signal notes/synthesizer sequence to _Close Encounters of the 3rd Kind_ ...



Road construction. The way they have it set up it is like going through a slalom course. You go left and right and back left in quick succession to get through there. Maybe I have a vacuum line loose and when I go through there it leaks a little causing the light to come on? Could be. When I do read the code it is already classified as an inactive code. I have cleared the code within a mile of it coming on and it reads as an inactive code.


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## KMixson (May 29, 2017)

The light did not come on this morning on my way to work. They were not working on the road this morning I guess due to the holiday. The slolam setup was still at the construction site but there was no one there. I am beginning to wonder what kind of chemicals they are using for the construction?


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## lovedr79 (May 29, 2017)

Interesting.


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## Captain Ahab (May 30, 2017)

KMixson said:


> The light did not come on this morning on my way to work. They were not working on the road this morning I guess due to the holiday. The slolam setup was still at the construction site but there was no one there. I am beginning to wonder what kind of chemicals they are using for the construction?




There maybe chemicals involved #-o


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## KMixson (Jun 5, 2017)

It did it again. Same place as always. They were working on the road this morning when I came through there. I don't exactly know what they are doing but it is screwing with my vehicle.


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## lovedr79 (Jun 8, 2017)

dang! that is crazy!


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## Johnny (Jun 8, 2017)

next time you drive through that area - roll down your windows
and turn off the A/C and see if you can smell anything like
fresh asphalt or any other "out of the ordinary" smells.

a few weeks ago, Central Florida had some pretty bad forest fires
and on one particular fire, the smoke plume was pretty high and 
a passenger jet from the Orlando airport flew through it . . . . 
the smoke fumes (maybe carbon monoxide?) was sucked into the 
plane and two flight attendants actually passed out, several passengers
started throwing up and the plane quickly turned around and made a 
distressed landing back at the airport ..... many went to the hospital 
with undetermined symptoms which later was determined to be from the ground fire smoke.

never can tell about these things - on land or in the air.

*if you were on Florida's East Coast, I would blame it on the Bermuda Triangle Complex. *



.


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## KMixson (Jun 8, 2017)

There is a very strong smell of asphalt when I go through there. There is no need to roll the window down to smell it. I think they tear up the asphalt at night and lay it back down before the morning rush. They work from 10PM to 6AM according to their caution signs. They are usually laying the asphalt back down at 4:15AM when I go through there. It is just a small section of road of about 100 feet in distance. They are working at laying a pipe underground across the road in my best guess. It is a four lane road with a center turn lane and right shoulders on both sides. As you approach it if you are in the far right travel lane you will cross the left lane and be in the middle turn lane and then turn back to the right to get into the right lane again all in the distance of about 100 feet.


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## Johnny (Jun 8, 2017)

I am far far FAR from being any kind of mechanic !!

but - does anyone think that if a loose or leaking vacuum hose could suck
in enough asphalt fumes to trigger the C.E.L. ??


.


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## KMixson (Jun 8, 2017)

Actually, I am a mechanic. A leaking vacuum hose could trigger the light even without sniffing asphalt fumes. That is why in an earlier post I mentioned the slalom type detour they have thinking that the side g forces may be causing a vacuum line to crack open just enough as I go through there to trigger the light. Now which one? That is the question? This car has some lines in some very hard to get to places. I dread going that deep into it.


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## Johnny (Jun 8, 2017)

I had to replace all the vac lines in my '97 Dodge Ram B3500 van
and I got about 10% into it and took it to the auto repair shop.
so yes - trying to find a leak is next to impossible. easier to just start
replacing the ones that are easy to get to and let a professional handle the rest.
in my case, I found a few of the little plastic connectors had cracked or broken.


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## LDUBS (Jun 9, 2017)

KMixson said:


> Actually, I am a mechanic. A leaking vacuum hose could trigger the light even without sniffing asphalt fumes. That is why in an earlier post I mentioned the slalom type detour they have thinking that the side g forces may be causing a vacuum line to crack open just enough as I go through there to trigger the light. Now which one? That is the question? This car has some lines in some very hard to get to places. I dread going that deep into it.



Can you duplicate the slalom turns in another area to see if the light comes on? If it does, then your suspicion will be proven. If not, then it is kinda like the twilight zone. 

One thing for certain. When trying to find something like this, it will always be in the last place you look. Hahah.


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## KMixson (Jun 9, 2017)

Yeah, what scares me is that the EVAP canister is above the fuel tank. You pretty much have to drop the tank to get to it unless you have tiny arms and are double jointed. You also have to get the car in the air on a lift to do it. That is even if that is the problem. I don't want to go through all that and it turns out to be something else.


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## Stumpalump (Jun 9, 2017)

The owners of yota and Honda believe that "they last forever". This leads their belief that oil changing and routine maintnence are a waste. Notice the cheapest China tires on the used ones. "Why buy a real tire when it eats them?" It eats them because the front end part that's been bad for 75,000 miles was never fixed. Pull a radiator cap. Yep...It has original corroded fluid. The car here has a problem. If it's not a gas cap then it's asphalt fumes..??.. Dude you have an evaporative emission code. You could drive over an oil well fire and it won't set that code. Swap parts or pay the $99 diag fee to let a local ASE guy smoke test it. It's not rocket science or hard to fix but it needs a lift, a smoke machine and a guy that fixed evaporate problems all week long. I fix most of my own stuff but that code is not worth buying and swaping the wrong parts. You might wind up with just a leaky hose anyway. In the meantime you are causing the worst of the worst pollution. Raw gas vapors. Can you say Boom! A shop will pump in smoke, actuate valves and look for the leak. If no leak then a few test points with a meter. Let a shop fix it. Oh but wait....Your a Toyota guy and they run forever. I'll make a bet...The thing is so run down and needs so many other service and repairs you don't have the balls to show up or have zero intentions to maintain it properly. Not trying to bust your balls but that's what I saw all day long when I managed a Midas. Pay for a diag. A minor fault code that gets neglected will hide a major one that may pop up and ruin your motor.
https://parts.olathetoyota.com/p0440-code-toyota


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## KMixson (Jun 9, 2017)

Stumpalump, I agree. I like to keep my vehicles in excellent mechanical shape. The problem with taking this car to the dealer or a local shop is the cost. Actually this is my girlfriends car. I bought a new Hyundia Sonata and gave it to her and I am driving her Toyota. I see the reason why so many people here are reluctant to take their car to be maintained is the extremely high cost. For instance, she had the right front brake caliper go bad and took it to the Toyota dealer here. She had it replaced for $3500.00 dollars. Since I have had the car the left front caliper went bad and I replaced it for $125.00. She also had an ignition key made for it one time and the cost was close to $300.00. I can get one for close to $20.00. 

Local shops are not much better. I had my A/C compressor clutch go out in my 1994 pick-up back in 2004 and took it to the dealer since I didn't have a vacuum system to reclaim the refrigerant at that time. They gave me a price of $1600.00 for parts only. I told them no. I had done my homework and the parts would only cost me $400.00. I then took it to a local shop and they gave me a price of $800.00. I told them to go ahead and fix it and left it with them. They called me that afternoon and told me they could not get the parts. So, I asked them if I bought the parts could they install them? They said yes. I bought the parts and had them install them and they only charged me $200.00 for the installation. I have my own vacuum pump, recovery machine, gauges and A/C tools now so I can do A/C work now. 

On another occasion I had my vehicle serviced at a Jiffy Lube one time and they put transmission fluid in the master cylinder causing every rubber part in the system to swell up and lock the brakes. They ended up paying the dealer for the repairs on that one. I had a nail get into my truck tire one time and took it to a tire shop. They wanted $45.00 to put a plug in it. That is why I am leery of auto shops.

I do pretty much any work on vehicles except rebuild automatic transmissions, front end alignment on passenger cars(although I do it for large class 8 trucks), and major body work. BTW, just a little background about me. I am the lead mechanic at Allied Aviation in Charleston S.C. I am contracted to maintain the fuel trucks that service the new commercial aircraft and maintain the fuel farm for Boeing in Charleston S.C. I also maintain fuel trucks at another small airport nearby.


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## Stumpalump (Jun 10, 2017)

I hate to recommend you to a Midas type place because but they charge a flat diagnostic fee. Once they quote you the problem you can call around for a part price or at least be informed so they don't rip you off. Hang out and let them show you the problem. Those problems take 2 minutes to 2 hours with every guy in the shop looking for the leak. That is why I said to pay for the diag. Another option is go online and get a 17.99 oil change coupon. Tell them the check engine light comes on. They sometimes trouble shoot for free hoping you will approve the $75 repair. I did that every day. That $3500 break problem...Could it have been a Master cylinder? Some of those are as rar as hens teeth and for common Toyota models. They come only from a dealer and yes it's thousands. Your other option is shot gunning the parts but what one? There are more specific forums that can lead you to what has fixed others. Next you break a nipple on a gas tank or canister or crack an odd hard line....I saw a few that were the tank pressure sensor. Gotta drop the tank. The other thing that fixes some is buying a gas cap from a dealer. It doesn't fix all of them but aftermarket gas caps are a real crap shoot. Your last option if you can pass emission inspection is to leave it unless you smell raw gas. Your problem is associated with raw gas and the fumes. It won't hurt anything if it's not leaking. Other codes like lean or my favorite thermostat errors are a problem. They don't fix the code for a bad thermostat but come back in 6 month and spend thousands to replace the cat that the cold engine ruined due to a rich condition.


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## KMixson (Jun 10, 2017)

I was going to take it to the Toyota dealer this morning but I think I will take it to Precision Tune after reading your post and see what they come up with. I did purchase a new Toyota brand OEM gas cap a couple of weeks ago and it still threw the code. As for sniffing fumes, the system is not sniffing fumes. It operates on pressure and vacuum. Fumes should not set off the light. My problem is it only does it at a certain location only when the construction crews are working. I have driven about a mile away from the construction site when the light comes on. That is odd. At first I was thinking the O2 sensor might me sniffing something but it would throw a different code if that was the case. I have recently been thinking maybe driving over the hot asphalt that has just been laid might be changing the pressure in the lines just enough to throw the code. 

The brake problem she had was just for the right front caliper. The master cylinder is still the original cylinder.


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## KMixson (Jun 10, 2017)

I had my car tested and they found no problem. They recommended replacing the vapor canister vent solenoid to "see" if that would cure it. This is what I was scared of. I can throw parts at it myself but I don't like to do that.


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## Johnny (Jun 10, 2017)

yikes ! a Toyota vapor canister is roughly $285.00 on line.


that is why I am NOT a mechanic !!!



.


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## KMixson (Jun 10, 2017)

Johnny said:


> yikes ! a Toyota vapor canister is roughly $285.00 on line.
> 
> that is why I am NOT a mechanic !!!
> 
> ...



And the bad part is that is is mounted above the fuel tank. That is why you have to drop the tank to replace it. You know, years ago you would open a hood and look at the engine. Now you open the hood and you have to dig for hours before getting a glimpse of the engine and it is continually getting worse. I work mostly on diesel trucks which are not quite as bad but seem to be going in that direction.


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## lovedr79 (Jun 10, 2017)

Vapor can is a pain to replace. Did one on a subaru once. Lots of vacuum lines.


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## KMixson (Jul 3, 2017)

Update. It did it again. I have not come through there in a couple of weeks and the light has not come on. As I was coming through there this morning it came on again. The construction is apparently wrapping up. Most of the equipment is gone and the road is straight again. They still have a few barrel markers off the side of the road. Maybe it is something else other than the construction? There is a BBQ place I pass there about a quarter mile from where the light comes on. Maybe they are cooking through the night to have to be able to serve the slow cooked BBQ. I don't know? I replaced the gas cap with a Toyota cap and had my car taken to be checked and Precision Tune found no problems with it.


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## lovedr79 (Jul 4, 2017)

Interesting. Will be interesting when they complete the work. Maybe your car is telling you to stop for BBQ


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## originalspacerob (Jul 7, 2017)

Most codes on the cars are tripped by specific scenarios. For instance. I got a code for my catalytic converter on my forester. It always happened on the highway and no where else. The car was purchased used from a dealer and had a 60 day warranty. I was not going to pay for a new Cat. So they check it and cant find anything twice. Reflashed the computer with new Subaru firmware. Took it for rides around the dealer. No luck. It will also go out after a few starts of the car. By this time i got the factory manual. Sure enough for every code there is a driving scenario used to replicate the code error if you have one. In my case. If you get this code to verify it you need to drive over 50 mph for at least 10 minutes before it will trip. I explained this to the dealer and they fought back a little. So I told them I would bring them a copy of the factory manual so they know how to check for it. They didn't like to hear that. Sure enough they take it on the highway and find the problem. Bad catalytic converter. Which cost them $1000. 
What i am getting at is the factory manuals have details like this. You could be just going in the right speed range, load on motor is just right and the sensors in the correct sensing mode and you trip the code because of those factors at that location. It may have nothing to do with construction, meth labs, pot smokers or pig smokers. Just the conditions and parameters on the cars systems at that time. Makes it hard to diagnose for anyone if thats the case. Only way would be to use a data logging scanner to see whats going on with the sensors and motor loads just before it trips. These types of repairs get very expensive at dealers because of labor. 
My suggestion: get a copy of the actual factory shop manual and see if there is a procedure to replicate this code and what parameters affect it. 


Sent from my iPhone using Tapatalk


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## lovedr79 (Jul 11, 2017)

originalspacerob said:


> Most codes on the cars are tripped by specific scenarios. For instance. I got a code for my catalytic converter on my forester. It always happened on the highway and no where else. The car was purchased used from a dealer and had a 60 day warranty. I was not going to pay for a new Cat. So they check it and cant find anything twice. Reflashed the computer with new Subaru firmware. Took it for rides around the dealer. No luck. It will also go out after a few starts of the car. By this time i got the factory manual. Sure enough for every code there is a driving scenario used to replicate the code error if you have one. In my case. If you get this code to verify it you need to drive over 50 mph for at least 10 minutes before it will trip. I explained this to the dealer and they fought back a little. So I told them I would bring them a copy of the factory manual so they know how to check for it. They didn't like to hear that. Sure enough they take it on the highway and find the problem. Bad catalytic converter. Which cost them $1000.
> What i am getting at is the factory manuals have details like this. You could be just going in the right speed range, load on motor is just right and the sensors in the correct sensing mode and you trip the code because of those factors at that location. It may have nothing to do with construction, meth labs, pot smokers or pig smokers. Just the conditions and parameters on the cars systems at that time. Makes it hard to diagnose for anyone if thats the case. Only way would be to use a data logging scanner to see whats going on with the sensors and motor loads just before it trips. These types of repairs get very expensive at dealers because of labor.
> My suggestion: get a copy of the actual factory shop manual and see if there is a procedure to replicate this code and what parameters affect it.
> 
> ...



the dreaded subaru P0420 code. that code disappeared after i replaced head gaskets.


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## originalspacerob (Jul 13, 2017)

Definitely not a head gasket in my case. My car is a 2011 with the FB25 motor. Doesn't have the head gasket problems of the older ones. 


Sent from my iPhone using Tapatalk


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## KMixson (Jul 31, 2017)

I did a test this morning on my way to work. I stopped about two miles before where the light comes on and made sure that there were no active or inactive codes thrown with my OBD II meter. All was clear. I drove through there as I normally would and like clockwork the check engine light came on. This is befuddling me. If I didn't see it I wouldn't believe it. After it came on I stopped and cleared the code and then drove the rest of the way to work without a problem. It will not come back on until I come through there next Monday morning. That is the way it works.


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## onthewater102 (Aug 2, 2017)




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## New River Rat (Aug 12, 2017)

I've read this thread and would almost bet that there is some form of electrical interference from, well, who knows what. It could be the road sign they use for info to drivers.







....or Ancient Aliens.....

.....or Rod Serling is buried nearby....(yeah, I'm _THAT _old.....)


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## lovedr79 (Oct 2, 2017)

still doing it?


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## KMixson (Oct 2, 2017)

Yes, it does. I have a video of it now and can't seem to get it uploaded to this site. It is MP4 format and I can't get it to load on here. I tried to convert it to MOV format but I can't get the whole video changed to that format without buying the full version of the converter.


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## gnappi (Dec 21, 2018)

My GF has a Toyota the would lock up the ignition (every time) trying to start it after she hit the parking space bumper on her last park. The "mechanic" told her it's a problem with Corollas and told her to not hit the bumper in the parking lot. 

The cause was the remote control battery power was strong enough to unlock the doors but not to disarm the security system. I replaced the battery in the remote nearly 2 years ago and it never happened again.


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## BillPlayfoot (Feb 23, 2019)

Two weeks ago I had that same error code 0440 on my 2003 Trailblazer. 
Replaced - fuel tank
- fuel pump/sending unit
- purge valve
- fuel lines
- fuel filter
- gas cap
- air filter
That problem solved.
Now the transmission down shifts and up shifts when driving at a constant speed. Speed up or slow down the transmission is fine. Thinking maybe the transmission solenoids are failing
If I had not just bought this Trailblazer in November I would have junked it. 
I have to learn that I cannot afford to buy cheap priced vehicles.


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## KMixson (Feb 23, 2019)

Update, My car still throws this code as I pass through that location. It is going on two years now. I guess I will have to live with it. I only pass through there once a week at the most so it is not too bad. Other than that the car is in excellent shape. It only has 85,000 miles on it. I have taken it on vacations and driven it a thousand miles and no code. As I mentioned in an earlier post I had it tested and they found no problem with the EVAP system. I am thinking it may be electrical interference from something there.


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## New River Rat (Feb 24, 2019)

.
.
.
August 2017:


New River Rat said:


> I've read this thread and would almost bet that there is some form of electrical interference



February 2019:


KMixson said:


> I am thinking it may be electrical interference from something there.



Makes perfect sense to me. :wink:


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## drewestin (Jan 12, 2022)

I need a program for my car service, I heard it is very convenient, is it true?


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## KMixson (Oct 17, 2022)

UPDATE! I have found the problem. It is the magnetic traffic light sensor mounted in the roadway on that lane. I was talking to an ASE Master Tech and he told me that could be the issue. I have been testing it over the last month. There are two southbound lanes and two northbound lanes and a center turn lane on the roadway there. As I am going to work at 3:00AM I am usually driving in the right lane across that sensor at that intersection due to no traffic on the road and the check engine light would come on every time. The past few weeks I have driven in the left lane as I went through there and the check engine light did not come on. This morning I was in the right lane and the check engine light came on like clockwork.


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## LDUBS (Oct 18, 2022)

I remember this thread and that it was a real head-scratcher. Thanks for the update!


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## MrGiggles (Oct 28, 2022)

The traffic sensor theory seems like a stretch to me.

I'd say it's more likely to me that specific point in your commute just happens to be when the conditions are met for the PCM to run the evap monitor.

P0440 is pretty simple, when conditions are right (fuel has to be at a certain level, vehicle has to have sat for a certain period of time so the fuel tank has equalized in pressure and temperature), the PCM will run the EVAP monitor, by closing the vent valve and opening the purge valve, which applies engine vacuum to the fuel tank and evap system. It will then close the purge valve and essentially start a timer, while measuring vacuum. If the system won't hold X amount of vacuum for X seconds, a P0440 or P0442 will set.

The diagnostic would consist of first verifying the issue with a bidirectional scan tool, and then smoking and pressure/vac testing the system through the test port to find the leak.


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## KMixson (Oct 28, 2022)

MrGiggles, I have had the car checked by two different shops and extensively by myself and they or I could find nothing wrong with the EVAP system. It has been smoke tested. I can drive it a hundred miles or a thousand and the code will not come on unless I drive through that intersection in the right lane. It would be very doubtful that I could "time" it to come on only at that intersection every time. It will not come on if I am in the left lane as I drive through there.


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## GTS225 (Oct 28, 2022)

How about in the southbound lanes or turn lane?
Just suggesting a more comprehensive and thourough test.

And I don't discount the magnetic sensor theory. As an industrial maintenance electrician (retired) I saw more than once where magnetic fields messed with DC electrics.

Roger


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## KMixson (Oct 28, 2022)

Yea, as a mechanic I have seen some weird stuff also. I was kind of hoping the car was sniffing the BBQ joint that I passed just before that intersection. It would be nice to have a car that alerts you to a BBQ joint nearby. BTW, here is the last video I took of the light coming on in that intersection.


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## MrGiggles (Oct 28, 2022)

KMixson said:


> Yea, as a mechanic I have seen some weird stuff also. I was kind of hoping the car was sniffing the BBQ joint that I passed just before that intersection. It would be nice to have a car that alerts you to a BBQ joint nearby. BTW, here is the last video I took of the light coming on in that intersection.



Hmm. It would be really interesting to graph the fuel tank pressure sensor with a scope while you drive through that intersection. Even just the PID for it in the datastream on your scanner may be enougHh to find any anomalies.


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## Stand Up (Oct 29, 2022)




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