P0496: Evaporative Emission System High Purge Flow

What Does P0496 Mean?

Code P0496 indicates that the EVAP system is purging fuel vapors into the engine when it should not be, or is purging at a rate higher than expected. This typically means the purge valve is stuck open, allowing fuel vapors to be drawn into the engine continuously. This can cause a rich condition and affect idle quality.

Common Causes

• Stuck-open EVAP purge valve/solenoid
• Faulty purge valve seal
• Cracked EVAP canister
• Leaking purge valve vacuum line
• ECM software issue commanding purge at wrong time

Symptoms

• Check engine light on
• Rough idle especially after refueling
• Difficulty starting when engine is warm
• Slight fuel odor
• Engine may run rich at idle

Diagnostic Steps

1. 1Monitor EVAP purge duty cycle with scan tool at idle (should be 0% when not commanded)
2. 2Check for fuel vapor smell in the purge line with engine off
3. 3Test purge valve by removing it and checking if it holds vacuum when de-energized
4. 4Inspect EVAP canister for cracks or saturation
5. 5Command purge valve open and closed with scan tool to verify proper operation
6. 6Check for TSBs related to EVAP system issues on your vehicle

Estimated Repair Cost

Frequently Asked Questions