What P0496 means
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.
How the engine computer detects it
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.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Check engine light on
- Hard or long starting right after refuelling
- Rough idle, rich fuel trim
- Hissing vacuum when opening the fuel cap
Common causes
- Purge valve leaking or stuck open (charcoal dust in the seat) Most likely
- Vent valve stuck closed or vent filter or line blocked Possible
- Vapour line kinked or blocked Less likely
- Tank pressure sensor reading wrong Less likely
How to diagnose P0496
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: evap purge valve, evap vent valve, fuel tank pressure sensor, engine control module.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Vehicles that report P0496 most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Chevrolet Traverse | 2011–2019 | 7 | — | |
| Ford Escape | 2019–2020 | 4 | — | |
| Ford Ecosport | 2018–2020 | 4 | — | |
| Buick Enclave | 2018–2023 | 3 | — |
Counts of owner complaints to the NHTSA that mention P0496 (30 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 4
- Auxiliary emission controls
- 96
- Specific fault
Questions drivers ask
Can I drive with code P0496?
Usually yes for a short time, if the car drives normally, the temperature gauge reads normal and the check engine light is steady. If the light flashes, the engine loses power or overheats, or other warning lights come on, pull over and have it checked.
Will my car pass an emissions inspection with P0496?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Will P0496 clear by itself?
The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.
Can I fix P0496 myself?
Often yes, with an OBD-II scanner and basic tools. Difficulty: easy. Start with the cheapest checks before replacing expensive parts.
Often reported together
Codes that owners mention in the same NHTSA complaints as P0496. They can point to a shared cause, so it's worth checking them together.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.