Check engine light

[Joe Wilson]

I've practically given up on repairing my 2004 Cavaliers emission system. The check engine light stays on and I don't want to pay for any more parts and still not get the problem fixed. Is there an easy way to disable the check engine light, at least temporarily and then hook it back up from time to time to run codes and see if I have any more problems? I'm tired of staring at the light knowing I can't do anything about it.

[jakegday]

well, what code(s) are you getting? and what repairs have you made in the attempt to fix this?

[J-Ri]

There is no way to disable it, short of reprogramming the PCM (and it's illegal for on-road use). Your best bet there is a little piece of black tape strategically placed on the instrument cluster

Since you said it's emissions, I'm guessing it's an EVAP emissions leak, although every code that turns on the light is emissions related. You'll never find the leak on one of these codes without a diagnostic smoke machine... unless a line is torn off or something.

But like Jake said, post the codes, maybe it's something we can help with.

[Joe Wilson]

Yeah, that's what it is, a leak in the canister system. I've looked and can't see or hear any leak, all the hoses appear to be ok. I've put on a new gas cap, with no results. I hear this is a common thing with these and one person posted that the repair is usually only good for a year or two before it acts up again. I don't have the expensive equipment and don't wish to spend a bunch of money at a garage. It runs fine, I'm just annoyed by that light. Tape might be the right approach. I just thought you might be able to take the light bulb out or something like that.

[J-Ri]

One thing you could try since they're cheap is just replacing the EVAP vent solenoid. They fail a lot, they get dust in them and stick open, causing a leak. The "filter" on them is just a chunk of foam.

Last I knew they were about $12 (slight commercial discount)

[Joe Wilson]

Is that the one in the back of the car to the right side? If it is, the part is more like $60. I priced it at Autozone. That's when I decided to not throw money at the problem.

[manicmechanix]

Like J-Ri said unless you see an obvious hole in the EVAP there's really no way to tell for sure where the leak is without the proper equipment. Might be cheapest to just take it to a reputable shop maybe a chevy dealer and ask for the diagnostic on the EVAP. They might be able to find your problem for under $70 diagnostic fee maybe.

[J-Ri]

Originally Posted by Joe Wilson

Is that the one in the back of the car to the right side? If it is, the part is more like $60. I priced it at Autozone. That's when I decided to not throw money at the problem.

dunno for sure where, I work on all sorts of cars, I know for the N and W bodies they're dirt cheap, or at least they used to be.

[Joe Wilson]

I checked Autozone.com again...The vent valve in the back of the car cost $44.99 and the one in the front in the engine compartment costs $28.95. I might splurge and buy the one by the gas tank since that's the dirtiest spot and I think the former owner of car lived on gravel road. They put that valve in a bad spot if it's affected by dust!

[J-Ri]

It is under the car, near the charcoal canister/fuel tank. It's not the location that does it so much (but it sure doesn't help any), it's the really cheap "filter" they use, some don't even have one. I've seen a few cars that were operated primarily on gravel, must have got 1/2 a cup of dust out of the charcoal canister on one. On a side note, see if they have a filter kit for the replacement valve, some do and some don't. Eventually the dust will plug the canister and you'll need one of those too, and they're pricey. Yours is probably still fine, they set an "EVAP purge flow performance" code when they get plugged to the point of not working.

The one under the hood is the canister purge valve, it's what opens to let the engine suck the vapors out of the canister. Those rarely go bad, when they do it's been all electrical problems that I've seen, and that has it's own code for short/open.