Evaporative Emission (EVAP) System Malfunction
What it means
The engine computer has detected a general fault in the evaporative emission (EVAP) system, which traps fuel vapor from the tank in a charcoal canister and later draws it into the engine to burn. The fault may be a leak or a valve that is not working, and it usually does not affect how the vehicle drives.
Related lights
Dashboard lights that may come on with this code.
Symptoms4
- Check engine light on.
- Occasional light fuel smell around the vehicle.
- Usually no driving symptoms.
- Failed emissions test.
Possible causes6
- Loose fuel cap or a cap with a damaged seal.
- Cracked or disconnected EVAP hoses.
- Faulty purge valve.
- Faulty vent valve or a blocked vent opening.
- Cracked or damaged charcoal canister.
- Faulty fuel tank pressure sensor or its wiring.
How to diagnose5
- Inspect the fuel cap and its seal, and tighten it until it clicks.
- Read other codes; more specific codes such as P0442 or P0455 narrow down the fault.
- Inspect visible hoses and the charcoal canister for cracks or disconnections.
- Command the purge and vent valves with a scan tool and confirm they respond.
- Have a smoke test done to locate any leak.
How to fix5
- Tighten the fuel cap or replace it with a correct one.
- Replace a cracked hose or reconnect a loose one.
- Replace a faulty purge or vent valve.
- Replace the charcoal canister if it is cracked or saturated with fuel.
- Clear the codes and drive until the EVAP self-test completes.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
In the Saudi market: SAR 40–1,200 (≈ USD 11–320)
Our prices come from the Saudi market, converted at a fixed rate (SAR 3.75 per USD). Prices in your country may differ a lot, so we show the cost level.
The fix is often a low-cost fuel cap; the cost rises when a smoke test and a new valve or charcoal canister are needed.
Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026
Frequently asked questions
Is this code serious?
No. It concerns emissions and usually does not affect the engine, but if you smell strong fuel odor, have the car checked soon.
Will the code clear after tightening the fuel cap?
It may clear after several days of driving once the computer retests the system. If it returns, the cause is elsewhere.
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