2009 Pontiac G8 3.6L with P0496 engine code, what can the problem be?

Question

4 months ago, something under the vehicle unplugged one the O2 sensors causing a warning message on my dashboard, and the mechanic plugged back, reset the computer and fine again, no problems. Although no error messages on dashboard, OnStar services has informed that there services indicates an issue is being detected with emissions control system not op as expected. O2 sensors have not been replaced since vehicle was purchased in Sep 2008. I was told by the dealer 3 years ago, that the knocking sound from the engine was at that time the evap valve, and that I should not worry, so what can the problem be?

Answer 1

P0496 Evaporative emission (EVAP) system flow during non purge

There are several causes for P0496 . one problem would be with the purge solenoid sticking and allowing a purge to occur when it is commanded closed, The other cause would be the fuel tank pressure sensor not reporting the true condition with the fuel tank pressure.

 Here a purge solenoid from a GMC product , if the solenoid sticks open it would set a P0496

 Another cause for P0496 is with the fuel tank pressure sensor. Inaccurately reporting the fuel tank pressure condition.

Answer 2

The P0496 code indicates a problem with the Evaporative Emission (EVAP) System. The EVAP system is designed to prevent fuel vapors in the gas tank from escaping into the atmosphere by channeling them to the engine for combustion. This code suggests that there is still a flow of emission gases even when the system is supposed to be sealed. The most likely causes for this code include:

• Faulty EVAP Canister Vent Valve
• Faulty EVAP Canister Purge Valve
• Clogged EVAP Canister
• Faulty EVAP Pressure Sensor

For more information about the code, visit the following link:

P0496 Pontiac Code - Evaporative Emission System Flow During Non-Purge
Read more: https://www.autocodes.com/p0496_pontiac.html