Ask Andy AIP0455 Evaporative Emission System Leak Detected (Large Leak)
What it means, what causes it, and what it costs to fix.
What P0455 means
The EVAP system can't hold vacuum at all. There's a big opening somewhere, or the system can't pull vacuum in the first place. A missing or loose gas cap is the classic cause.
Can I drive with P0455?
Severity: Low. Not urgent. Fix it when convenient.
Safe to drive. Expect a fuel smell, and you'll fail an emissions test until it's fixed.
Get a diagnosis for your exact car
Tell Andy your year, make, model, and symptoms. You'll get best case, most likely, and worst case, with parts and labor costs. Free, in about 15 seconds.
Ask Andy about P0455Symptoms
- Check engine light
- Noticeable fuel smell
- Sometimes trouble refueling (pump keeps clicking off)
Common causes
Most likely first.
- Gas cap missing, loose, or damaged
- Disconnected or split EVAP hose
- Purge valve stuck closed
- Vent valve stuck open
- Cracked filler neck or canister
How to diagnose P0455
- Check the gas cap first. Then clear the code and drive a few days.
- Inspect the EVAP hoses at the engine (purge valve) and at the tank and canister.
- Smoke-test the system to pinpoint the opening.
Tip: most US auto parts stores will read your codes for free.
Repair costs
| Gas cap | $15–$40 |
| EVAP hose reconnect or replace | $0–$200 |
| Purge or vent valve | $100–$350 installed |
| Filler neck | $250–$600 installed |
Typical US prices. Your vehicle, region, and shop rates will change these.
P0455 FAQ
What does P0455 mean?
P0455 means "Evaporative Emission System Leak Detected (Large Leak)." The EVAP system can't hold vacuum at all. There's a big opening somewhere, or the system can't pull vacuum in the first place. A missing or loose gas cap is the classic cause.
Can I drive with a P0455 code?
Safe to drive. Expect a fuel smell, and you'll fail an emissions test until it's fixed.
What is the most common cause of P0455?
The most common cause is: Gas cap missing, loose, or damaged. Other causes include disconnected or split evap hose and purge valve stuck closed.
How much does it cost to fix P0455?
Typical repairs run about $0 to $600 in the US, depending on the cause. Gas cap: $15–$40.
Still not sure what's wrong?
Describe the noise, smell, or warning light, or snap a photo. Andy is free to try.
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