Emissions

P0496 — EVAP Flow During a Non-Purge Condition

Severity: low Safe to drive

What P0496 means

The engine control unit monitors the evaporative emission (EVAP) system using the fuel tank pressure sensor and fuel trims. The purge valve is supposed to stay closed unless the engine is warm and conditions allow purging. If the data shows vapor still reaching the intake, P0496 is set. The usual culprit is a purge valve that is stuck open or leaking.

Symptoms

  • Rough idle, especially after refueling
  • Hard starting when the engine is hot
  • Rich fuel trims at idle
  • Check Engine light on
  • Fuel smell if the problem is large

Possible causes

  1. Purge valve stuck open or leaking
  2. Vacuum line routed incorrectly after a repair
  3. Failed purge solenoid
  4. Damaged wiring or connector at the valve
  5. Other mechanical fault in the EVAP system

How to diagnose

  1. Make sure the fuel cap is seated and in good condition
  2. Read scan data: fuel tank pressure, fuel trims and freeze frame
  3. Inspect the vacuum lines for correct routing and damage
  4. Check the purge valve wiring, connector and coil resistance
  5. Command the purge and vent valves with a scan tool and verify they respond
  6. Apply vacuum to the valve with power off to see if it holds
  7. Smoke-test the EVAP system for leaks

Common fixes

  • Replace the purge valve
  • Reroute or replace the vacuum lines
  • Repair the valve wiring or connector
  • Replace the fuel cap or any other faulty EVAP component

Questions and answers

Can I drive with a P0496 code?

Usually yes, but get it repaired soon. Excess vapor can make the engine run rough, start poorly and use more fuel.

What most often causes P0496?

Most often it is a purge valve that does not seal fully. Check the hoses and fuel cap too.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.