Leaky IAC Valve and DTC P0440.

[s_simms]

I have a 2000 cavalier 2.4L that has been throwing DTC p0440 for a while now, and after addressing the common problems (fuel cap, vent valve...) I could never seem to find the source of the problem.

Recently while diagnosing an unrelated problem I found that the o-ring on the IAC valve was damaged and obviously leaking. Since I replaced this o-ring and reset the MIL, P0440 has yet to come back (over a week now).

I was just wondering if it was even possible that a leak around the IAC valve could be the cause of P0440 being thrown.

[jdl]

I wouldn't have thought that o-ring would cause the 440 code?

Did you check the vent solenoid harness? There is a service bulletin for the 440 code, relating to that harness. On some vehicles, that harness was misrouted, causing some chaffing damage.

Do you have a plastic gas tank?

You said the code was gone, now, maybe it won't come back.

[s_simms]

Yeah, I tend to not believe the IAC valve leaking would have anything to do with an emission's system code. I'm sure that eventually that pesky code will pop back up.

I've checked all the obvious possible problems (vent solenoid harness, purge solenoid) and replaced the vent solenoid (which was seized) and gas cap.

Only thing left is to get a smoke test done and maybe get the fuel tank pressure sensor checked. By the way my tank is plastic.

[jdl]

There was also a bulletin for the o-ring seal on the plastic gas tanks, where the fuel sender unit goes. You may already have the updated seal. I probably wouldn't fool with it, unless I was sure it was causing a problem. I believe it was a 442 code that was associated with that seal.

[vargasking]

I have an '01 Cav and having the same pesky P0440 code coming back. I still have to have a smog check b4 getting my new tags. How/where do I check the service bulletines before going to the dealer. These dealers would often try to avoid doing those free repairs. Where is the IAC valve located?