Check Engine Light - 4 Error Codes - Please Advise!

[mayberry97]

2006 Aveo.
Runs perfectly.
35+ MPG consistently.
I get an intermittent Engine light.

When it happens:
- Each time i fill up the tank.
- I re-seat the gas cap and it goes away.
- Drive about 100 miles and it comes back.
- Unplug the battery for a bit and it goes away.
- 100 miles later it comes back.
- Replace the cap, and it goes away...and again, comes back later.

Also:
- Fuel gauge wanders up and down after filling the tank. Once it's down halfway, it settles in normally.

What i've done so far:
- Replaced the gas cap with a standard new one, with a locking new one, and it does not make a difference.
- Wrapped the filler nozel with thick plastic and tightened with a rubber band to ensure that it is airtight. It goes away for a bit then comes right back.

Had the ECU read. Getting 4 error codes:
- P0463 = Fuel level sending unit condition
- P0110 = Air Intake Temp circuit
- P0442 = EVAP small leak
- P0456 = EVAP small leak detected

Are these codes inter-related? Is there one part in particular that i can replace that will satisfy all 4 of these codes? I really would appreciate any help you can offer.

Thanks...

[Daox]

My first guess would be to look at the evap system since it sounds like you have a leak. That could take care of a few of the codes. After fixing that I'd re-diagnose to see what problems remain.

[petrified.rabbit]

if the gas cap fixes it, even temporarily, replace the gas cap. And not with a locking one, it might not be sealing correctly either. $15 and it might make the problem go away.
it could just be the loss of pressure in the fuel system setting three of those codes caused by a leaking gas cap.

the only one i see that is not directly related to tank pressure is the P0110 = Air Intake Temp circuit code. It might be wired in though, but it might just be a coincidence light (how the low fuel tank pressure is effecting the engine).

so replace the gas cap first, then see what it is doing and report back. have you had a fuel pump or anything replaced recently?

[mayberry97]

Thanks for the replies. I replaced the gas cap twice now and the light goes out for a bit, then comes back. Being that the problem still occurs when the filler is sealed with plastic, could it still be a gas cap issue? I'm thinking that it must be somewhere else...

As for recent repairs...the only thing that has been replaced was the timing belt. I bought the car from the original owner with 80,000 miles on it. He never replaced the belt. So i had the dealership replace it a few days later. The light did come on after that when i filled the tannk, but i didn't really have the car long enough to say that it wouldn't have come on anyways.

Is there an online diagram that might show the EVAP system? To be honest, this car is way over my head. I'm used to carburetors. I can't even identify most of what's under the hood.

[petrified.rabbit]

If you had the head done, check the purge valve and evap lines in the engine compartment.

They could be damaged, hooked up incorrectly, or something.
If the dealer has documented that the problem has persisted since the repair, they could check the system for you.

[mayberry97]

Thanks for the reply. I didn't have the head done. I took it to the dealership to have the timing belt replaced and the light wasn't on beforehand...but only because i hadn't filled up the tank yet (i just bought it a few days prior). So there is no documentation regarding this.

I guess i could take it to the dealer, but i doubt they'll even look at it without costing me.

Do you know of an online diagram to identify the purge valve and evap lines? I checked all of the hoses and didn't see any that were cracked or damaged, but i'm not sure exactly the ones i should focus on.

[petrified.rabbit]

yeah i meant timing belt, but was on my iphone..

the evap stuff, is all in the rear wheel well behind the tire and splash shield, then has lines that run up to the front of the car with the fuel lines. I am not sure where the purge valve is on your year though.