P0455: EVAP System Leak Detected - Large Leak
Standardized SAE J2012 code · P04xx — Auxiliary emission controls
What does P0455 mean?
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.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Check engine light on (possibly a check fuel cap message)
- Possibly fuel smell
- EVAP readiness or emission inspection not passed
Common causes
- High Fuel cap missing, not clicked in or seal faulty (or capless flap)
- High Hose off or cracked (canister, filler neck, purge line)
- Medium Vent valve stuck open or purge valve stuck closed
- Medium Canister or filler neck cracked or corroded
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of P0455 on the same make and model first.
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