P0496: EVAP System High Purge Flow

The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air. P0496 means vapour flows into the intake although the module is not purging – usually a purge valve that leaks or sticks open. GM and Saab seal the system after a cold start with the engine running; if tank vacuum exceeds 2491 Pa for 5 s, the code sets (fuel 10–90 %, MIL after two trips). Ford, which replaced its old code P1450 with P0496, also sets it for excessive vacuum during the leak test, for example with a vent valve stuck closed. Hard starting right after refuelling is typical.

Low severity. Can I keep driving?Yes, you can normally keep driving. If there is a strong smell of gasoline, find the leak before continuing and do not smoke nearby.

Symptoms

Check engine light on
Hard or long starting right after refuelling
Rough idle, rich fuel trim
Hissing vacuum when opening the fuel cap

Most likely causes

Purge valve leaking or stuck open (charcoal dust in the seat)
Vent valve stuck closed or vent filter or line blocked
Vapour line kinked or blocked
Tank pressure sensor reading wrong

What to check, in order

Start with the simplest. You can tick off each step.

Start with the fuel cap: tighten it fully and check its seal
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
Inspect the hoses and connections around the tank and the charcoal canister
Use the scanner to test the purge and vent solenoid valves
Run a smoke test to find small leaks

Good to know

Repair difficulty: easy
It affects emissions.

What each character of P0496 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
4: Emissions
96: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0496?

Yes, you can normally keep driving. If there is a strong smell of gasoline, find the leak before continuing and do not smoke nearby.

What causes code P0496?

The most common causes are: purge valve leaking or stuck open (charcoal dust in the seat); vent valve stuck closed or vent filter or line blocked; vapour line kinked or blocked.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.