Powertrain, generic · Auxiliary emission controls

P0496 EVAP System High Purge Flow

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

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

Symptoms

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

Repair estimate

DifficultyEasyDIY possible
Parts and labour€50–250
Time0.3–1.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

evap purge valveevap vent valvefuel tank pressure sensorengine control module

Related codes

P0497P0441P0443P0455P0446P0498

References: gsi.ext.gm.com, saabwisonline.com, saabwisonline.com, fordservicecontent.com.