P0496 code: EVAP flow during non-purge condition

What P0496 means

P0496 is a generic SAE code: Evaporative Emission System High Purge Flow, often listed as "EVAP flow during a non-purge condition". The EVAP system stores fuel vapor in a charcoal canister. A purge valve between the canister and the intake opens when the engine computer wants to burn those vapors and stays closed the rest of the time.

During its self-test, the computer closes the purge valve and watches the fuel tank pressure sensor. If the tank starts pulling vacuum anyway, engine vacuum must be getting through a valve that should be shut. That sets P0496. Use our code decoder to look up any other codes you see.

Symptoms of P0496

Many cars with P0496 only show a check engine light. When there are other symptoms, they usually show up right after a fill-up, because a leaking purge valve lets a large amount of fuel vapor into the intake.

• Check engine light on
• Hard starting or long cranking right after refueling
• Rough idle or stalling shortly after a fill-up
• Fuel smell from the engine bay on some vehicles
• Lean or rich fuel trim codes such as P0171 or P0172 on some vehicles, from unmetered vapor or air entering the intake
• Trouble filling the tank, with the pump nozzle clicking off early, on some vehicles

Common causes of P0496

The purge valve is by far the most commonly documented cause. Check it first.

How to diagnose P0496

A scan tool with live data and active tests makes this code much easier to confirm. Look at our guide to the best bidirectional scan tools if your reader cannot command the EVAP valves.

1. 1

   Read and record all codes and the freeze frame data. Note any fuel trim codes or other EVAP codes.

2. 2

   With the engine at idle, watch the fuel tank pressure sensor reading in live data. If it moves toward vacuum while the purge duty cycle shows 0 percent, the purge valve is likely leaking.

3. 3

   Locate the purge valve. On many vehicles it is in the engine bay on or near the intake manifold. Disconnect its hoses and electrical connector.

4. 4

   With the valve unpowered, try to blow through it or apply vacuum with a hand pump. A normally closed purge valve should hold. If air passes freely, it is stuck open.

5. 5

   If the valve seals when unpowered, check whether it is getting constant power or ground when it should be off. A shorted control wire can hold it open.

6. 6

   Look for charcoal granules in the hoses. If you find them, the canister is breaking down and can ruin a new valve.

7. 7

   Repair, clear the codes, and drive normally so the EVAP monitor can run. Check readiness monitors before an inspection.

Note.Work on EVAP parts with the engine off and cool, away from sparks and flames. Fuel vapor is flammable.

How to fix P0496

Most P0496 repairs are a purge valve replacement. On many cars the valve is held by one or two clips or bolts and has two hoses and one connector. Location and design vary by vehicle, so check the service information for yours. If the canister is shedding charcoal, replace it too, and clear any granules from the lines.

After the repair, clear the code. If the car was hard to start after refueling, that symptom should go away. Clearing the code without a fix will not help for long, because the EVAP test will run again and reset it.

Can you drive with P0496?

Usually yes, for a short time. The engine normally runs fine once it is warm. The risk is the hard start or stall right after refueling, which can be a problem at a busy pump or when pulling into traffic. Fix it soon, and see can you drive with the check engine light on for general guidance. If the light starts flashing, stop driving and have the car checked.

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Related codes

Codes that often appear alongside P0496 or cover nearby parts of the EVAP system: P0455 (large leak), P0456 (very small leak), P0442 (small leak), P0446 (vent control circuit) and P0171 (system too lean, bank 1).

Frequently asked questions

Is P0496 always the purge valve? No, but a stuck or leaking purge valve is the most common cause. Test the valve before buying parts, and check the wiring if the valve seals when unpowered.

Why does my car stall after getting gas with P0496? Refueling fills the canister with vapor. If the purge valve leaks, that vapor flows straight into the intake and makes the mixture too rich, which can make the engine hard to start or rough for a short time.

Can I clean a purge valve instead of replacing it? Some people try, but if the valve is stuck from charcoal debris or wear, it usually comes back. Replacement is the standard fix.

Will P0496 fail an emissions test? Yes. Any stored emissions code that turns on the check engine light will fail an OBD2-based inspection in most US states.