Hello.

I am really hoping someone can point me in the right direction here. My check engine light went on several months ago with a p0440 code. A few years back I already did the whole harness/wiring breaking & replacing thing, so I looked at all the hoses, wires and everything and saw nothing obvious or unusual. Drove around all these months with no problems at all and nothing causing any concern but here in Raleigh, the car must pass an emissions test to renew the registration so I knew I was going to have to deal with it. Well for the last 6 weeks, that is what I have been trying to do since the weather has been better and warm enough to do so. I have read and re-read everything online that has anything to do with this whole thing and spent an insane number of hours trying to get to the problem. I brought it to the dealer and they tested the purge and vent valves and did a smoke test and found nothing wrong and everything working fine but the car still was going to fail the test so they suggested spending $200 to replace the vent valve solenoid thinking perhaps some dust or dirty was preventing a tight seal. I went to the Zone and bought a new vent valve and changed that out myself 3 days ago and the CEL is still on.

So here are my first set of questions: I have all kinds of detailed information about the drive cycle for this GM car and still don't really understand a couple of things. Before I did any work on the car, I had the codes cleared and the CEL came back on after the car had sat overnight for 2 nights - about 48 hours from the time I had them cleared. So I figured that the same time period and driving behavior/roads/speed, etc... would be required for the light to go OUT after the part change. Is the requirement for the CEL to go out after being on the same or different from vice/versa? They gave me hard time when I finally (3rd place I tried) got someone to clear the codes, so I wasn't going to go back after changing the part - but is that necessary and/or won't the light go out by itself if the part I changed was the problem?

The second question is obviously - if everything checked out, AND I just wasted the time, effort and money on a new Vent Valve for no reason - then WTF is causing the problem since there are no leaks? The dealer said the next item to replace - going down the expensive list (which I cannot afford and that is why this has become a crisis for me with 6 days left until my registration expires) - would be the fuel tank pressure sensor. And he made it sound like that would be more expensive than the whole car's value to get done.

Any help, or suggestions would be greatly appreciated. I have spent the last 3 days driving around in circles on the interstate hoping to get the light to go out since the vent valve change but nothing has been solved and I am going out of my mind.

thanks

What is the year, model and engine and trans of your car? That will help with some ideas


2002 Pontiac Sunfire SE Sedan 2.2l Ecotec 4 Speed Auto.

An FTP sensor is only like $50 I think but you have to drop the tank. It's basically a 2 bar map that goes on the tank.

Have you tried a gas cap?




"A car just isn't a car without a little blood, sweat, and beers." -- Shadowfire

Sorry my bad on the lack of basic info.

The car is a 2001 Chevy Cavalier 2.2 with 174K and runs great.

The first thing I did was to buy a new gas cap and that was a waste - which I figured it would be.

Also, once I had the old (and probably just fine) vent valve off the car, I started it up with a rubber glove over the hose sticking out of the canister to test whether with that sealed-up, a vacuum would be created and sure enough - when I took the gas cap off, I huge whoosh / air being sucked in sound that I had never heard before happened which left me cautiously optimistic that when I put the new vent valve on, it would solve the problem.

My main urgent question remains about the driving cycle - and/or what it takes to get the light to go OUT assuming the problem is fixed. I have read every possible combination of different information - anywhere from you have to have the codes reset because the EVAP monitor will never run if there are any codes present - to you have to start the car 40 times - to it will go out by itself after two cold start/complete driving cycles. It is the last of those that has me kind of panicking right now - since that is how the light came back on after I had the codes reset and before I had done any repairs.

So again - does anyone know the true story? I feel like this whole check engine light thing is a big inside joke that everyone is in on, except me.

Thanks again.

You could take it to any advance auto/auto zone and they will clear the codes for free in a few minutes. You could also just removed the battery cable for a few minutes, the complete a new drive cycle. The complete drive cycle list is pretty crazy, but if you just start it up cold, drive it around for a little, then do about 20-30 miles on the highway above 55mph you should be good to go. Unfortunately EVAP is the only monitor that takes forever to set. You may need to drive it around for a week until it actually comes back up.

Last thing I'll mention is that there could be a loose wire that connects to the evap canister. That wire is notorious for breaking. Replacing that wire if its broke will fix the issue if you find it's still not resolved after resetting everything this time around.



"In Oldskool we trust"

if the evap actually takes that long to set, i would clear the code, drive 15 min and go pass emissions and be done.

Personally, i would recommend getting a cheap $20 scan tool. In the end, clearing the code and passing emissions that way would have been almost $0 cost.




"A car just isn't a car without a little blood, sweat, and beers." -- Shadowfire

I had the same problem as the OP with my wife's 01 Cavalier 2.2. Ended up being the fuel filler neck, which was rusted and apparently leaking. $130 for the part, cleared the CEL, drove around for a day, then passed the emission test no problem.

I had already spent $250 on diagnostics and new parts and I was right back where I started from, so this morning, I went back to the Chevrolet dealer to spend an additional $110 on more in-depth diagnostics because the CEL and p0440 are both still going on. They came back and said it was the PCM and it would cost an additional $600 to replace and program that with a new one. I couldn't afford that - since I already couldn't afford what I had already spent.

So I am out $300 and it is like I haven't done a thing and my registration expires in 3 days.

So my question NOW is: Has anyone else replaced their Cavalier PCM? Where can you get one? How much is just the part? How hard is the job? Is it something you can even attempt or do yourself or does it require some specialized programming and/or computer software that only GM has?

Thanks.

It's cake to physically replace and they can be had from other members here for around 50 bucks. I'd check with your local yards and see what is available. Is this car a manual or automatic transmission? If it's an automatic, it's right off the passenger side strut tower. If it's a 5-speed, it's under the plastic wheel well liner on the passenger side. Don't let that scare you, it's pretty easy to get to; every bolt is 7mm just like the interior. After that, you may or may not have to do the "relearn procedure" which goes as follows:

1.Start, let it die (passlock will disable the car), leaving the key in the ON position
2. Observe the flashing "theft" light until it stays on solid
3. Leave key on for 10 minutes until theft light goes out
4. Turn key OFF for 10 seconds
5. Turn key to ON (without starting) and leave it on for 10 minutes.
6. Repeat steps 4 and 5.
7. Turn key OFF for 10 seconds
8. Attempt to start, car should have relearned and will remain running until you turn the key off.

Sometimes with the PCM people get lucky and don't have to do the relearn. Just have to try it and see what happens.

All that being said, I find it really hard to believe that a bad pcm would cause these issues. I still think there's a problem elsewhere and they just gave you this bogus answer knowing that you won't pay to have it done anyway.



"In Oldskool we trust"

Thank you very much Y3ellowCav for the info. I was getting the feeling that there might not actually be anyone on here who both reads all the details of the info supplied with the question and/or actually knows anything useful. Nice to find out that fear isn't always right.

You very well could be right about them just telling me that because they knew I was just gonna take off. I pretty much told them that I was interested in passing the emissions test and that I wanted to pay as little as possible to do it - and if it was something really expensive, I was just going to move to a county or state that didn't require emissions testing. On top of that, the same tech who worked on it 10 days ago was the guy they put on it again for two more hours today. I was really hoping for someone else just in case this guy didn't know what he was doing.

I just read some threads on here regarding PCM replacement and they all sound like you need to have a GM dealer/tech with all the bells and whistles to "flash" them once their in - otherwise you are in deep trouble just cold swapping them out of another car of the same model. Mine is a 2001 2.2 5-speed stick which is in great condition and this is the first major issue I have had - and it really is only an issue thanks to the damn emissions blocking registration. If my county didn't require it, I could have avoided the whole damn thing and be would still have the 300 bucks as well as all the years that the last 10 days have taken off my life.

Now I have more research to do and a lot of big decisions to make. I love how problems and expenses like this are totally dependent on where you live.

Thanks again.

i put the gas cap off my 01 z24 on my 02 LSS when it came up, and the light went out after 3 miles. lol. $7 gas cap and its done! glad i was lucky