P0455 means the engine control unit has detected a large leak in the evaporative emission system. This is a more significant leak than P0442, often caused by a missing fuel cap, a completely disconnected EVAP hose, or a cracked charcoal canister. The large leak size usually makes it easier to find.
P0455 means the engine control unit has detected a large leak in the evaporative emission system. This is a more significant leak than P0442, often caused by a missing fuel cap, a completely disconnected EVAP hose, or a cracked charcoal canister. The large leak size usually makes it easier to find.
P0455 is a evap system-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0455 and illuminates the check engine light.
If your vehicle has triggered P0455, you may notice one or more of these symptoms:
Here are the most common causes of P0455, ranked by how likely they are to be the culprit:
Generally yes, for short-term driving. A large EVAP leak does not affect driveability, but it means significant fuel vapour is escaping. Check the fuel cap immediately. Repair before your next emissions inspection.
Follow these steps to pinpoint the root cause of P0455:
Repair costs for P0455 vary depending on the root cause and your vehicle. Here are typical estimates:
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0455 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:
These codes are often seen alongside P0455 or indicate related issues:
It is not mechanically harmful and will not damage your engine. However, a large EVAP leak means significant fuel vapour is escaping into the atmosphere. The check engine light will cause an automatic failure at any EU vehicle inspection.
If the cap was loose or missing, yes. Tighten it until it clicks and clear the code. The ECU will re-test the system over the next few drive cycles. If the code returns, there is an additional leak beyond the cap.
The ECU categorises leaks by size. P0442 is a small leak (equivalent to a pinhole), while P0455 is a large leak (equivalent to a 1mm or larger opening). Large leaks are usually easier to find because they often involve a disconnected hose or missing cap.
The most likely reason is that the fuel cap was not tightened properly after refuelling. On some vehicles, overfilling the tank (topping off past the first click of the nozzle) can also saturate the charcoal canister, triggering EVAP codes.
If the cause is a fuel cap, the fix costs 10 to 40 EUR. A hose replacement runs 40 to 170 EUR. A charcoal canister replacement is 120 to 480 EUR. Start with the cheapest possibility first, as the fuel cap is the culprit in a large percentage of cases.
EVAP leak causing a check engine light? P0442, P0455, P0456 explained. Start with the gas cap. Causes, diagnosis, and repair costs in euros.
Learn how OBD2 works, find the port in your car, understand diagnostic trouble codes, know which problems you can fix yourself, and when to see a mechanic.
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