P0455 code meaning
EVAP System Leak Detected - Large Leak
Powertrain system Generic code P04xx codes Check engine light
What P0455 means
The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air. P0455 means a large leak or that no vacuum builds up. Ford pulls the closed system down with engine vacuum and expects about −2 kPa within 30 s; after refuelling it sets P0457 instead. GM sets the code if 20 litres have been purged without reaching 2740 Pa tank vacuum (once per cold start, MIL after two trips). Saab's ME9 uses a pressure drop below 525 Pa. The code also covers blocked purging, for example a purge valve stuck closed.
P0455 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.1 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P0455
- Check engine light on (possibly a check fuel cap message)
- Possibly fuel smell
- EVAP readiness or emission inspection not passed
Common causes of P0455
- Most likelyFuel cap missing, not clicked in or seal faulty (or capless flap)
- Most likelyHose off or cracked (canister, filler neck, purge line)
- PossibleVent valve stuck open or purge valve stuck closed
- PossibleCanister or filler neck cracked or corroded
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EVAP systemFuel capEVAP hosesEVAP purge valve
What each part of P0455 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 55 | The exact fault in that area. |
What to do next
- Note P0455 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0455
What does P0455 mean?
P0455 means "EVAP System Leak Detected - Large Leak". The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air. It is a generic code, so it means the same on every make.
Is it safe to drive with P0455?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0455 fail an emissions test?
Yes, it can. P0455 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0455 to fix?
Difficulty: easy. A typical repair takes 0.1 to 3 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0455 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.