Code P0496 Definition
EVAP Flow During a Non-Purge Condition
What Does P0496 Mean?
The Evaporative Emission Control (EVAP) System seals the fuel system of the vehicle in order to prevent fuel vapors from the fuel tank and fuel system from escaping into the atmosphere. This is important because fuel vapors contain a variety of hydrocarbons. Hydrocarbons form smog when they react with air and sunlight. Gasoline evaporates very quickly, so if the fuel system is open to the atmosphere a vehicle can pollute 24 hours per day without even being turned on. These uncontrolled evaporative emissions account for as much as 20% of the pollution produced by a vehicle! When trouble code P0496 is set, it means that there is an issue with the purge flow in the EVAP system. Specifically, the Evaporative system is purging fuel vapors when it shouldn’t be.
What Are The Symptoms Of P0496?
There may not be any noticeable driving issues with your vehicle, but your engine could be running rich which could cause Catalytic Converter damage. It may also be hard to start the vehicle.
What Is The Cause Of P0496?
- Faulty EVAP Purge Volume Control Valve (most common)
- Faulty EVAP pressure sensor
- Leaking EVAP system hose
- Poor electrical connections
- Leaking Charcoal Canister
How Serious Is Code P0496? – Low
Although there are no apparent driving issues with this trouble code, it should still be addressed as soon as possible so that there is no damage to the catalytic converter.
Code P0496 Common Diagnosis Mistakes
Replacing the EVAP Purge Volume Control Valve before checking to see if it is leaking.
Tools Needed to Diagnosis Code P0496
How To Diagnosis And Repair Code P0496:
Difficulty of Diagnosis and Repair – 2 out of 5
- Reset the Check Engine Light to see if the Check Engine Light returns in the future.
- If the code returns, test the Purge Volume Control Valve for a Stuck Open condition. With the key and engine off, remove the hose going to the Purge Volume Control Valve coming from the fuel tank and unplug the electrical connector to the valve. (performing this test may set another code if it does, clear the code and disregard it until after the test is completed and the vehicle is put back together). Now, start the engine and use either a vacuum gauge or your finger to see if the vacuum is coming out of the Purge Volume Control Valve where you removed the hose. If there is a vacuum, then the Purge Volume Control Valve is leaking and needs to be replaced. If there is no vacuum you could still have an intermittent failure of the Purge Volume Control Valve or another EVAP system issue. Continue the diagnosis on the next step.
- Perform an EVAP system leak check: Pinch off the vent tube to the EVAP Vent Control Valve. Pressurize the EVAP system with an EVAP smoke machine leak checker. Check to see if you see any smoke leaking out from any hoses or seals. If there are any leaks, repair leaks and check to see if the concern is resolved.
- If you find no leaks, then grab your digital multimeter and back probe the EVAP Pressure sensor signal wire. Remove the EVAP Pressure Sensor from the Charcoal Canister or disconnect the hose going to it and apply a slight amount of pressure to the sensor using the pressure hand pump. You should see the voltage change as you do this. (consult the service manual for your vehicles spec on what this voltage should be) If it is not in spec, replace the EVAP pressure sensor.
- If the concern persists after these checks, it may be time to take the vehicle to the shop to have it diagnosed.
Estimated Cost of Repair
For error code P0496, one or more of the below repairs may be needed to solve the underlying issue. For each possible repair, the estimated cost of repair includes the cost of the relevant parts and the cost of labor required to make the repair.
- EVAP Purge Volume Control Valve $150-$200
- EVAP Line $20-$100
- EVAP Pressure Sensor $280-$330