P0449 code on 08 Trailblazer

CorkyE

Veteran Member
Lifetime Gold Member
Nov 4, 2004
11,931
Ringgold, GA
Evaporative Emission System Valve/Solenoid System

Not getting a gas cap code along with this one, but I checked anyway, it's on tight. What are some of the most common causes? Looks like Saturday may the a long day trying to chase this down. Thanks
 

Twisted_Metal

Administrator
Staff member
Lifetime Gold Member
Feb 26, 2004
31,884
Bloomington, MN
Check the gasket surface on the gas cap.

My Impala threw an evap/emissions code a couple of months ago and I found small cracks in the gas cap gasket.
A new cap actually fixed it. :D

The faulty evap purge valve or a cracked hose is the next things to check for.
After that... There's probably a pressure sensor in your gas tank which can go bad.

Note: This is just guesswork as I don't know all of the components of an 08 Trailblazer system.
 

CorkyE

Veteran Member
Lifetime Gold Member
Nov 4, 2004
11,931
Ringgold, GA
Okay, I'll check the gasket tonight, I just made sure it was on tight. Doubt my luck will let me off that easy. :(
 

Knuckle Dragger

Mayor of Simpleton
Staff member
Lifetime Gold Member
Nov 2, 2002
16,993
Waddell AZ
GM had a problem with the valves on the Tahoes and Silverados and redesigned it. I suspect since you got the code for the valve and not a leak it's electrical with the valve. Likely water got into valve or connector. I have no hands on with a Trailblazer though.
 

danbrennan

Veteran Member
Lifetime Gold Member
Mar 13, 1999
5,077
Brighton, MI
We took my wife's 2008 Trailblazer in for the evap code this past summer, and they said they replaced the line, the gas cap, and the solenoid. But the code came back after a month or so. It's interesting in that now when we fill up the gas tank at the gas station, the engine initially won't start - the ECM times out the starter engagement. But then if we turn the key again, it starts okay. So far we've only noticed this when we fill up with gasoline. Maybe somehow the fuel system is leaning out too much at start, because it's not sure of the evap pressure?

Anyway, I'm curious to hear what you find. My wife just hasn't got around to taking her truck back to the local repair shop, and I have enough other things to do.
 
Last edited:

1980RS

Veteran Member
Jun 17, 2006
6,635
MN
Sometimes on cars and trucks from back then, charcoal from the canister gets dislodged and gets stuck in the solenoids. We used to have a lot of that with P0446 codes but mat pertain to this one also.
 

tom3

Veteran Member
Aug 1, 1999
15,151
ohio
Sometimes just overfilling the tank will cause this. Gets a slug of gas in the lines and throws the code. I've learned (hard way) to just fill until it clicks off then stop. No problems since. Knock on wood.
 




Latest posts

Top