P0455Low severityEmissionsDIY: Easy
P0455: Evaporative Emission System Large Leak Detected
Same family as P0442 but a bigger leak. Start with the gas cap, then look for disconnected EVAP lines or a stuck-open vent valve.
Can I keep driving?
Yes in most cases. It will not affect how the car drives, but fix it so fuel vapors are not escaping.
Symptoms you might notice
- Check engine light, often right after a fill-up
- A fuel smell near the car
- Gas cap that does not click or seal
What to check first
- Check that the gas cap is on, undamaged, and fully tightened. A cap left loose after fueling is the classic cause of a large-leak code.
- Look for a hose that has popped off, especially around the fuel tank filler neck and the charcoal canister.
- If the cap and hoses are fine, the vent valve or purge valve may be stuck open, which usually takes a scan tool or smoke test to confirm.
Most common causes
- Missing or badly worn gas cap
- Disconnected EVAP hose
- Failed vent control valve
Check it against your exact vehicle
A code means the same thing on every car, but where the parts are and what to check first depends on your year, make, model and engine. Tell CaliperAI what you are seeing and it will help narrow down the likely causes for your vehicle.
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General information about this code, not a diagnosis of your specific vehicle. Safety-critical work such as brakes, fuel and airbags is best left to a qualified mechanic.