Code P0449

johndeere844 · February 27, 2008

I know this has been asked alot on here and i have been looking at them but what exacatly does it mean/ Is it electrical or mechanical or could it be a combination of them both. I had a mechanic tell me it was the little sensor on the top of the engine 12582627 so i replaced it and still nothing checked the fuse 4ws and it wwas good have not checked for power yet am going to do it tommorow. Can i unplug the sensors and test the power there with the key on?. Thanks for all your info and help this is a awesome site.. By the way its a 2004 sierra ext cab 4x4 5.3l. This all started the morning after washing and fueling up my truck. Also does anyone know if it is covered under gm extend warranty plan i bought it as a optimum used with a 2 year 40 km custom warranty. Thanks again

gmtech4 · February 27, 2008

you HAVE TO take it to the dealer and find out if its covered ,thats it,don't spend any more money on it if you have a extended or other optimum plan,ok?,take it in ,make an appointment,please.

minibike132 · February 27, 2008

A p0449 indicates an electrical failure, and you don't have to take it to the dealer. You only need to take it there if you don't want to pay for it. You bought the warranty let the warranty do it's job for you. Hell I fix em and with my warranty I still pawn it off on someone else.

johndeere844 · February 28, 2008

Thanks very much for the help guys. On my way home today the CHECK FILLER CAP message came on so i stoped at a gm dealer and bought a new gas cap. Ten minutes later out went the light. So $70 later instead of the $100 deductible on the warranty its fixed. Now if only i could turn off the goverenor so i can go faster than 160km that would be great. I apperciate the help thanks again.

minibike132 · February 28, 2008

If you had a p0449 it will come back. Right church wrong pew. This code relates to the evap system and yes a faulty fuel filler cap will cause evap codes. The p0449 specifically deals with the electrical circuit for the vent valve.

A battery positive is supplied to the evaporative emission (EVAP) canister vent solenoid valve. The control module grounds the EVAP canister vent solenoid valve control circuit to close the valve by means of an internal switch called a driver. The scan tool displays the commanded state of the EVAP canister vent solenoid valve as ON or OFF. The control module monitors the status of the driver. If the control module detects an incorrect voltage for the commanded state of the driver, this DTC sets

That is the circuit description for this code direct from GM. The tests that run this code couln't care less if you have a hole in the fuel tank the size of a watermellon it only cares that it sees proper voltage being returned on a solenoid circuit. It is possible that you had 2 issues happen at roughly the same time.

johndeere844 · March 1, 2008

Well all my hope in the fuel cap went to crap driving home tonight it came on about 5 minutes after tighten feul cap came on. I am booking it in next week let them handle it. It also has some weird clunking noise coming out of the steering column so let them fix that too.

johndeere844 · March 8, 2008

I thought i would update this problem. I was bored at work today and decided to check things out my self. I got out the voltmeter and started checking voltage. Had power coming out of the 4ws fuse and so i went to the fuel tank and to my suprise there was no vent solenoid there so i started to follow the hose and wire followed it back up to under the hood!!!!!! unpluged it and had no voltage went down the line to where they had spliced it and found it had corroed in one of the splices cut the bad section out put it back together heat shrinked it and cleared the code and voila no more CEL. I wonder why they had relocated it to under the hood? And also should i move it back to proper spot or just leave it? Thanks to all the info on here i was able to trace it down. Thanks alot.

gexline21 · March 13, 2008

it was probably moved trying to keep water from getting in it and making it stick. there is no real reason to move it back if it works fine now. Future refernece P0449 is a circuit failure not a leak in the Evap system.

I thought i would update this problem. I was bored at work today and decided to check things out my self. I got out the voltmeter and started checking voltage. Had power coming out of the 4ws fuse and so i went to the fuel tank and to my suprise there was no vent solenoid there so i started to follow the hose and wire followed it back up to under the hood!!!!!! unpluged it and had no voltage went down the line to where they had spliced it and found it had corroed in one of the splices cut the bad section out put it back together heat shrinked it and cleared the code and voila no more CEL. I wonder why they had relocated it to under the hood? And also should i move it back to proper spot or just leave it? Thanks to all the info on here i was able to trace it down. Thanks alot.