P0455 Evaporative Emission System Leak Detected (Large Leak)
P0455 is a generic OBD2 powertrain code. It means “Evaporative Emission System Leak Detected (Large Leak)” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker.
Ask the AI about P0455 on your car- System
- Powertrain (P)
- Code type
- Generic (SAE)
- Range
- P04xx
- Urgency
- Low
What P0455 means
The EVAP system — the fuel tank, the charcoal canister, the purge and vent valves and the hoses between them — keeps fuel vapor out of the air. The computer tests it by sealing it and watching the pressure; it found a large leak (P0457: the fuel cap is loose or missing).
Symptoms
- Usually nothing but the lamp
- Sometimes a smell of fuel around the car
- A failed emissions inspection
Most likely causes
- A gas cap that wasn’t clicked shut, is missing, or has a cracked seal
- A disconnected or split EVAP hose
- A vent valve stuck open
- A purge valve that doesn’t seal
- A cracked charcoal canister or filler neck
What to check first
- Tighten the cap until it clicks (or replace one with a hardened seal) and clear the code
- Give it a few days: the leak test only runs under specific conditions — typically after a cold start with the tank neither nearly empty nor full — so the lamp won’t go off at once
- If it comes back, a smoke test of the EVAP system finds the leak
Can I keep driving with P0455?
Safe to drive — fix it when convenient
Yes. It’s a vapor leak, not a drivability problem — the only consequences are a whiff of fuel and a failed emissions test.
How P0455 breaks down
Powertrain. Engine, transmission, fuel and emissions — the codes behind the check engine lamp.
Generic code: defined by SAE, the same on every make.
Auxiliary emission controls.
The specific fault within this range.
Where to look: Auxiliary emission controls
The systems that clean up exhaust and fuel vapor: exhaust gas recirculation (EGR), secondary air injection, catalytic converter monitoring, the evaporative emissions (EVAP) system with its purge and vent valves — plus exhaust temperature sensors, the particulate filter and some cooling-fan circuits.
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Frequently asked
What does P0455 mean?
P0455 is a generic OBD2 powertrain code. It means “Evaporative Emission System Leak Detected (Large Leak)” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker. The EVAP system — the fuel tank, the charcoal canister, the purge and vent valves and the hoses between them — keeps fuel vapor out of the air. The computer tests it by sealing it and watching the pressure; it found a large leak (P0457: the fuel cap is loose or missing).
Can I drive with P0455?
Yes. It’s a vapor leak, not a drivability problem — the only consequences are a whiff of fuel and a failed emissions test.
What causes P0455?
A gas cap that wasn’t clicked shut, is missing, or has a cracked seal; A disconnected or split EVAP hose; A vent valve stuck open; A purge valve that doesn’t seal; A cracked charcoal canister or filler neck.
How do I clear P0455?
Fix the cause first, then clear it with any OBD2 scanner or app. Once the fault is gone the car also clears it on its own: the check engine lamp goes off after the self-test passes on three drive cycles in a row, and the stored code ages out after about 40 warm-ups. Clearing without a repair only hides it for a while — and resets the readiness monitors an emissions inspection looks at.
Is P0455 the same on every car?
Yes. P0455 is a generic SAE J2012 code, so its definition is identical on every make and model. What differs is the cause behind it and the repair procedure, which depend on the engine — that’s why the assistant on this page asks for your car.
Guides
Definitions: the generic SAE J2012 codes from Brimly’s offline dictionary (data version 2026.09). Causes and advice are general guidance for all makes — the service information for your car has the last word.