Pontiac Grand Prix OBDII code Diagnosis

This is one of the most commonly encountered trouble codes for the Pontiac Grand Prix The Code P0496. The code refers to a number you receive when your Grand Prix is plugged into an OBDII scanner.

Pontiac Grand Prix Symptoms

A frequent symptom of P0496 in Pontiac Grand Prix engines is an intermittent idle. In order to determine the right idle speed, the engine may rev up or down. This can often occur right after buying gas. The gas station might also not be able to start it.

If you’re old enough to have driven a carbureted vehicle the old stomp the gas and crank the engine method does actually help start the car. The air fuel mixture is off.
Related: Pontiac Grand Prix P0420

Pontiac Grand Prix - P0496 Meaning

P0496 stands for a universal OBDII Trouble Code. It means that the code is universal and will be the same regardless of make or model. Technically, the code stands for:

Evaporative emission system High Purge Flow

The EVAP system collects fuel vapor from your fuel tank, and then sends it to the intake of the engine to ignite the combustion process.

If the Pontiac Grand Prix computer notices that the EVAP is not purging properly, it will issue the OBDII code P0496.

Pontiac Grand Prix Causes

Many things can lead to the P0496 problem code on Pontiac Grand Prix. The most frequent problems that cause this code are listed below.

Vapor Canister Purge Valve– The most common culprit with the P0496 trouble code and the Pontiac Grand Prix is going to be the vapor canister purge valve. When it goes bad, it typically causes issues with the vehicle’s idle speed. It is particularly true after filling up your vehicle.

It’s really easy to replace. You will need to locate and delete a few clips. Below is an excellent YouTube video that explains how to diagnose the problem.

PCM– It is possible that the engines computer system itself has gone bad and is registering a P0496 when it shouldn’t be. This is not the place you should be starting.

The wiring– It is possible for shorts in the wiring harness leading to the Vapor Canister Purge Valve has gone bad. It is worth checking.

Fuel Cap– A bad fuel cap can cause the P0496 code to be thrown for sure. Often, you’ll get a message informing you that the fuel cap is off even when it is on. It may be worth your time to change the fuel cap on your Pontiac Grand Prix to see if it disappears.

Oil Tank Pressure Sensor– If the fuel tank pressure sensor has gone bad, it can cause all sorts of problems, including the P0496 code.

Here’s a good video on it:

We wish you all the best in finding out what's wrong with Grand Prix. This should help. You can add any additional information by leaving a comment.