Question about Toyota Cars & Trucks
There is a VSV (vacuum switching valve) , usually mounted on the back side of engine block, under the intake manifold, as well as the map sensor, that can also cause that code if one or the other is faulty. It takes some pretty detailed troubleshooting to confirm this in some cases, so if that's not in your line of work, you may have to have it properly diagnosed, or take a 50/50 shot at which one first.
Posted on Jan 24, 2009
check air filter for dirty , how many miles or kms have your car? , maybe need to replace spark plugs, try to reset the ecu for a momentany malfunction, remove the negative battery terminal few minutes and reconnect,start engine and drive, check if lights goes off , please write me
Posted on Jul 05, 2009
did u change the right o2 sensor there is 2 sensors on bank1 and 2 on bank2.....upstream and down stream.....i had the same prob i changed the o2 senser to the other side to check and make sure it was the o2 senser....it took 4 o2 sensors before i got 1 that finally worked nd yes i was buying them brand new.....so change sides with it nd see if the code changes sides....and did u reset it with the code machine when u put the new 1 in?
Posted on Mar 28, 2010
Testimonial: "i wont no if this is a successful answer until i can reset the code thank you"
SOURCE: I HAVE A 2007 GMC
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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