P0455 Code: Evaporative Emission Control System Leak Detected (Large Leak)
🟢 Low severity · drivable
Safe to drive — this is an emissions leak, not an engine problem. Fix it before your next emissions test.
What P0455 means
The evaporative emission (EVAP) system has a large leak, meaning fuel vapors are escaping. It's usually something simple like a loose gas cap or a disconnected hose.
Symptoms
- Check engine light is on
- Possible fuel smell
- Usually no driving symptoms
Common causes
- most common: Loose, missing, or damaged gas cap
- common: Disconnected or cracked EVAP hose
- common: Faulty EVAP purge or vent valve
- less common: Crack in the charcoal canister or filler neck
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Tighten or replace the gas cap | Yes | $10–30 |
| Inspect and reconnect or replace cracked EVAP hoses | Yes | $10–60 |
| Have a smoke test performed to find the exact leak | Mechanic | $50–150 |
| Replace a faulty purge or vent valve | Yes | $30–120 |
Frequently asked questions
Can I drive with a P0455 code?
Yes. It's an emissions leak and doesn't affect how the car runs. Fix it before your next emissions test.
What is the most common cause of P0455?
A loose or missing gas cap. Always check the cap first — it's the cheapest and most common fix.
Is P0455 expensive to fix?
Usually not. Most fixes are under $150. It only adds up if the charcoal canister or fuel tank itself is cracked.
Related codes
P0456
P0456 Code: Evaporative Emission System Leak Detected (Very Small Leak)
P0442P0442 Code: Evaporative Emission Control System Leak Detected (Small Leak)
P0440P0440 Code: Evaporative Emission Control System Malfunction
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.