Evaporative emissions (EVAP)
P0455
Evaporative Emission System Leak Detected (Gross Leak)
What does P0455 mean?
P0455 means the evaporative emissions system has a large leak — big enough that the computer could not build or hold any meaningful pressure at all. It is the same system as P0442 but a much bigger opening, which usually means a missing fuel cap or a disconnected or split hose rather than a pinhole.
Can I keep driving with P0455?
Low urgency
Not a driving hazard, but fuel vapour is escaping — check the cap is present and properly seated before paying for any diagnosis.
Symptoms of P0455
Check engine light, typically with normal driveability
A noticeable fuel vapour smell, especially after filling up
Failed emissions test
Common causes of P0455
A missing or completely unseated fuel cap
A disconnected, split or rodent-chewed EVAP hose
A vent valve stuck open
A damaged charcoal canister
These are ordered roughly by how often they turn out to be the cause — but the code names a system, not a part. Confirming which one is yours takes data from the running engine.
What does it cost to fix P0455?
$20 – $600
Typical US independent-shop range, parts and labour included. It is wide on purpose: the cheap end is usually a sensor, a hose or a cap, and the expensive end is the major component the code was reporting on. Which one you need is a diagnosis, not a guess — and dealer rates run higher than these figures.
What does P0455 mean for your car?
This page explains what P0455 means in general. It cannot tell you which of those causes is yours, because that answer is in your car's own data. Kaiju Mechanic reads the codes your car is actually storing, plus live sensor data through any standard ELM327 adapter, and interprets it against your exact year, make, model and mileage. You can also just ask it about P0455 in chat — no adapter needed for that.
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