2004 Denali With P0442

mhorn0817 · September 21, 2009

welp, i have done some searching around here and found some answers but none that have fixed my CEL for code P0442. I checked all the hoses and everything, didnt see any cracks or holes or leaks. Gas cap is and has been tight. I replaced the purge valve solenoid. i ordered from the dealer, dealer part number 12581282. looks identtical but seemed more loose then the stock purge vavle solenoid. i did have the battery disconnected when i swaped it out. started back up and CEL still on. any other ideas, help,input would be great!!

ColoradoSkiCountry · September 21, 2009

Just a thought or two:

Go ahead and replace the Gas Cap. the rubber seal may look good on it but oftentimes they will fail and the system will not stay pressurized. Make sure you get a good quality gas cap too! Oftentimes aftermarket locking caps have poor rubber seals. Just a FYI.

Second- Just because the problem may have been fixed does not mean the CEL will go off. That code needs to be cleared out of the computer with the right tool. I learned from a trusted ASE Master Tech that people often think that simply disconnecting and re-connecting the battery or fixing the problem will clear the CEL light but more then not this will not clear the code.

Hope this helps in some way or another!

mhorn0817 · September 21, 2009

1. - i never recieved a "tighten fuel cap" message on my display, should i still replace anyway. also where and what kind of gas cap should i get?

2. - that is true, i will get the code cleared tomorrow and see if it pops back on

spikesputnik · September 22, 2009

Just a thought or two:

Go ahead and replace the Gas Cap. the rubber seal may look good on it but oftentimes they will fail and the system will not stay pressurized. Make sure you get a good quality gas cap too! Oftentimes aftermarket locking caps have poor rubber seals. Just a FYI.

Second- Just because the problem may have been fixed does not mean the CEL will go off. That code needs to be cleared out of the computer with the right tool. I learned from a trusted ASE Master Tech that people often think that simply disconnecting and re-connecting the battery or fixing the problem will clear the CEL light but more then not this will not clear the code.

Hope this helps in some way or another!

What he said, replace the cap anyways. I just did mine and had it cleared at Advance, hasn't come back after a dozen starts now