Question about GMC Yukon
DTC P0496 - Evaporative Emission (EVAP) System Flow During Non-Purge
If the EVAP purge valve does not seal properly, fuel vapors could enter the engine at an undesired timing causing drivability concerns. The control module tests for this by commanding the EVAP purge valve OFF closed and vent valve ON closed, sealing the system, and monitoring the FTP for an increase in vacuum. If the control module detects that Evap system vacuum increases above a calibrated value, DTC P0496 will be set.
This could be a sign that your purge valve is intermittently failing so you might want to get it checked out before it turns into a bigger problem that affects the drivability of your truck.
EVAP is located behind the throttle body, near the front of the engine...
Fig. Front engine compartment view-4.8L, 5.3L, 6.0L and 6.2L engines (1) Throttle Body (2) Manifold Absolute Pressure (MAP) Sensor (3) Evaporative Emission (EVAP) Canister Purge Solenoid Valve (4) Knock Sensor (KS) (5) Engine Block Heater (6) Engine Coolant Temperature (ECT) Sensor (7) Camshaft Position (CMP) Sensor (8) Generator (click for zoom)
The first step would be to simply clean the valve and see if that helps. The purge valve will be an inexpensive part (probably $20.00 or so) so I'd usually just replace it instead of trying to test it to thoroughly. I've found it can be a somewhat tough part to come by a third party dealers (Napa, Autozone, etc.) So you might have to contact your local GMC dealership parts department to buy the part.
The best thing to do would be to ask the person at the repair dept who sells you the part to copy the page with the replacement guidelines from the service manual. You usually won't have any trouble getting them to do this and then you'll have a good written copy to follow while you change the valve.
The other option would be to have a local mechanic do the replacement for you.
Posted on Nov 04, 2010
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Posted on Jan 02, 2017
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