p0455.. what check engine light code is that???

 

P0455 is Evap Leak Monitor Large Leak Detected A large leak has been detected in the evaporative system.


Here is a link to the site i pulled it from.... very helpful

http://www.clubavalanche.com/forums/...howtopic=3940&

 

i just took my truck to the shop acouple days ago with that exact same problem.. they said it was a faulty gas cap and they SAID they fixed it.. but now i have that problem again!!!

 

I think this gas cap diagnoses gets over used. Yes, it is possible for a faulty gas cap to cause a 455 error code. This is because the evap system is giving tank evaporations a place to go. If the gas cap is not functioning properly it is allowing a leak in the system.

If the light was off when you got it back it's becasue they cleared the code form the engine. If it came back that means they did not fix the problem. Either you got a new cap that was faulty (not likely) or you have a leak somewhere else in the system.

 

I had P0442 evaporative emissions control system leak detected (small leak), now that was a gas cap problem for me. Yours has to something worse than a gas cap. The best thing to do is to have a smoke test done to fined the problem.