My 2010 CTS 3.0l just threw a P code for EVAP Purge Valve High - P0496. Normally this requires cleaning or replacement of the EVAP Purge Valve. This time I found the vacuum pipe connecting the EVAP to the air intake had came loose. This line connects on the drivers side rear top side of the engine. Once reconnected I cleared the code and so far it has not reoccurred.

Lesson - check vacuum lines often to ensure they have not become disconnected.

A good link on OBD codes and this P code in particular is:

http://www.obd-codes.com/p0496

 

welcome and thanks for sharing

 

Looks like I made a mistake above post. This vacuum tube is part of the PVC system and connects to the valve cover on the drivers side of the engine.

The P0496 code is back.

When I filled up last time, my car did not want to start (cranking but did not start) until I held down the gas pedal.

Earlier when I filled the tank, the car did start but idle was very rough until I pressed the gas pedal and revved the engine.

Could this all be a be a bad EVAP purge control valve?

 

possibly if it was causing a vacuum leak. Try clean throttle bore. If there is a lot of carbon it can cause pedal to be depressed to start engine. There is a special policy related to throttle body which MAY apply you could go by dealer and see.

 

I replaced the EVAP Purge Valve located on the top of the engine on the passenger side. The old valve was stuck in the open state. Simple to replace. So far, my CTS is behaving properly. I still need to fill up and see if it has a hard time starting. Seems to be a similar problem to a post in the SRX section of the forum.

 

I also have the 2010 CTS 3.0 and about to replace the canister purge valve..I have not replaced this before on this vehicle. Easy to do? Location?? Thanks!!