P0455
PowertrainEvaporative Emission Control System Leak Detected (Gross Leak)
There's a large leak in your evaporative emissions (EVAP) system, petrol vapour is escaping in significant volume.
ⓘ Information only. This page provides general educational information about fault code P0455. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0455 mean?
P0455 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Evaporative Emission Control System Leak Detected (Gross Leak).
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light
- • Often a noticeable smell of petrol
- • Drivability is unaffected
Possible causes
Causes commonly associated with P0455, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Fuel cap missing, very loose, or seal damaged (most common)
- 2. Cracked, disconnected, or split EVAP hose
- 3. Faulty purge valve stuck open
- 4. Damaged fuel filler neck
- 5. Faulty charcoal canister
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Check the fuel cap first, missing or loose caps cause this code very often
- 2. Inspect EVAP hoses visually for any obvious damage or disconnection
- 3. Workshop smoke test will locate larger leaks reliably
Common questions about P0455
What's the difference between P0455 and P0442? +
Both are EVAP leaks; P0455 indicates a 'gross' (large) leak, P0442 indicates a 'small' leak. Both have similar causes but P0455 is more likely to be a missing fuel cap or disconnected hose.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →