lefty51

Just reading this thread I had an observation. The hhr evap system works this way. The purge valve (or solenoid) is located on the drivers side of the engine. It gets a signal to open and engine vacuum "pulls" vapors from the canister to burn instead of venting them to atmosphere. When doing this it creates a vacuum in the fuel tank. The tank is always under a little negative pressure when car is running. When vacuum gets high enough (I can't remember the Hg number) the purge valve reduces "pull". The Valve (or solenoid on the canister is the vent valve. It opens to allow outside air in to counter tank vacuum and allow purge valve to pull vapors from canister. If you have a purge pulling to much or a vent valve not venting OR a clogged canister it will throw a code and when you shut your car off you maybe able to hear your fuel tank groaning as vacuum subsides. My wife says it's how I sound when trying to get up out of my chair If I have this right the purge valve works by opening and closing in increments, while the vent valve is open or closed. The key is what code is set. There should be one for purge and one for vent. Of course if your lucky like me, purge valve went bad, replaced it, then vent valve went bad. well not really bad vent valve, but that a long sad story about dealer replacing fuel pump. for what it's worth.

donbrew

The problem is there are several codes that can lead to either/both/other things. The OBD EVAP test just tests the pressure and the rate of change, It could turn out to be a leaking EGR tube.

OBD does not test the solenoid or vent electrically at all, it just tells you "something is wrong go find out what it is."

lefty51

Your right, donbrew, even the tech 2 will give you the sames codes as it reads the OBD. the only difference is the tech 2 will let you test the circuit. It seems like the purge valve is the "first" fix. Either because it's the easiest or it is the most common component to fail because it works the most. The 07 hhr had the fuel pump replaced 2 years before I bought it by a chevy dealer and the previous owner told me it would throw the gas cap code as he called it. And he said whenever he filled the tank up it would leak and smell of gas. He took it back and they said there was nothing wrong with the install, could find no problem and did not want to drop the tank. He finally gave up and lived with it. I wouldn't have, but. Anyway I was getting the purge valve code, eventually dropped the tank and found the pump just sitting on top of the tank, the retaining ring just sitting there. The only thing holding the pump in was the tank pressing up against the body. I will say it was a bear getting the pump to seat into the tank. When it was finally fixed it ran fine and then threw a code which did turn out to be a purge valve. Ran fine and then the vent valve stayed closed, which turned out to be from years of driving on gravel roads. I blew dust out of the canister and vent valve forever. it was running fine but is throwing a code again, I think it is the canister as I don't know if blowing air through it helped or was good for it. Anyway as you said when it throws a code in the evap system it can be misleading. I guess replace enough parts and you'll fix it. At least I'm not leaking gas anymore !

donbrew

One important thing to add to the "how-to" is that they changed the wiring harness to the EVAP solenoid sometime around 2009.

Now the replacement part available is the NEW connector, an additional pigtail/adapter is required for cars that came with the OLD design.

Beefjerky

Never had any evap or emissions codes but always a real bad fuel smell where vent valve line is. I replaced the rear vent valve the engine bay purge valve and carbon canister with new revised models and blew out the lines. At times i still get a fuel smell outside by fuel door.Ive never had a car do this i think the rear vent valve is opening when it shouldnt maybe needs the computer firmware updated??? I have little babies gasoline fumes are very toxic. I also installed new timing solenoids i thought i connected them wrong but with your help i realized i did connect them right but now i still get the engine light going on and off and fumes coming now from intake manifold and throttle body. This is our only car This dam car has me like kramer on seinfield. Someone please help

whopper

If you have the Engine Check light on, you need to get the code(s) downloaded to determine what the current issue is.

I've replied to your other post regarding the problems with the solenoids, and deleted your duplicate posting of the above post in the other thread to lessen confusion in trying to follow your problems.

Looking at the issues you have encountered with replacing the solenoids, I'd suggest you take it to a dealer to sort out your various issues. Ïf you just want to get the codes read, pretty much any auto parts store will do that for free (but be aware that they may not interpret the code right, and may sell you the wrong part).

Pylonman

Got the PO455 Code. Replaced the purge valve in the engine compartment.
Next step, change out the EVAP Canister Purge Solenoid. Did it during the weekend with these handy instructions. Everything worked fine until I went to plug in the 12V DC power port. The stock purge solenoid had a molded figure "8" style of male and female port. The replacement part was a square male and female.
So, when ordering your part and your parts person takes it out of the box, check to see if it's the same as on your car. See picture below for close up.

I had to blow out the existing solenoid with the air compressor a re-install. If was full of super fine dust, charcoal?

donbrew

See post #34

tuffnuts59

changed EVAP canister filter, light sill on. what is next.

donbrew

Why is the light on?
The CEL is on because a code has been set. What code is set?