P0496
Evaporative Emission System High Purge Flow
Low· Fix when convenientDIY friendlyPowertrainGeneric, all makes
What it means
The evaporative emission (EVAP) system traps fuel vapour from the tank in a charcoal canister and later burns it in the engine. The ECU periodically seals the system and checks that it holds pressure or vacuum. Vapour is flowing into the engine when the purge valve should be closed. The valve is almost always stuck open.
Is it safe to drive?
Safe to drive, but the engine may stall or be hard to start right after refuelling.
Symptoms
- Check engine light on
- Hard starting or stalling after refuelling
- Rough idle
Probable causes
Most likely first
- 1Purge valve stuck open
- 2Charcoal from a broken canister jamming the purge valve
How to diagnose it
Work through these in order before buying parts
- 1Record the code and its freeze frame data (speed, load, temperature when it set), then clear it and see if it comes back.
- 2Apply vacuum to the purge valve with it unpowered. If it does not hold, it is stuck open.
- 3Check for technical service bulletins (TSBs) or software updates for your make and model; some codes have known factory fixes.
Common fixes
- Replace the purge valve
- Replace the canister if charcoal is found in the lines
This information is general guidance for all makes. Exact causes, specifications and procedures vary by vehicle, so confirm with your service manual or a qualified mechanic before replacing parts.