What does P0455 mean?
During a self-test, the computer seals the EVAP system and checks whether it can hold vacuum or pressure. A large leak means it could not, often because the fuel cap is missing, loose or not sealing.
Codes are a starting point. They tell you which test failed, not which part to replace. Check for other stored codes and fix those in a sensible order.
Symptoms
- Check engine light
- Possible fuel smell
- Hard starting after refueling (with purge problems)
- No change in how the car drives in most cases
Common causes
- Loose, missing or damaged fuel cap (most common)
- EVAP vent valve stuck open
- Purge valve stuck open or closed
- Disconnected or cracked EVAP hose
- Rusted or cracked filler neck
- Cracked charcoal canister
How to diagnose P0455
- Check the fuel cap and its seal first.
- Run a smoke test, the most reliable way to find EVAP leaks.
- Command the purge and vent valves with a scan tool and check that they open and seal.
- Inspect the filler neck and hoses under the vehicle.
How to fix it
- Replace the fuel cap
- Replace cracked hoses
- Replace the purge or vent valve
- Replace the charcoal canister or filler neck
Estimated repair cost
Likely repairs for P0455 run from about $15 to $700, depending on the cause.
| Repair | Typical range (parts + labor) |
|---|---|
| Fuel cap replacement | $15 - $45 |
| EVAP smoke test | $100 - $200 |
| EVAP purge valve | $100 - $300 |
| EVAP vent valve/solenoid | $100 - $350 |
| Charcoal canister replacement | $250 - $700 |
These are rough US estimates for an independent shop in 2026, based on typical parts prices and standard labor times. Dealers, big trucks, luxury brands and high-cost areas often run higher. They are not quotes. Use the repair cost estimator to adjust for your vehicle.
How serious is P0455?
Low severity
Safe to drive. It will fail an emissions test until fixed.
Make-specific notes
GM (Chevy, GMC trucks and SUVs)
The canister vent solenoid near the charcoal canister is a common failure, especially on vehicles driven on dirt roads.
Ford
The canister vent solenoid and the purge valve are frequent causes. Some Fords use a capless filler that can collect dirt and fail to seal.
Toyota
Check the fuel cap first; a cracked canister or leak detection pump problems are less common causes.
Always check open recalls and technical service bulletins for your VIN.
P0455 FAQ
Will tightening the gas cap fix P0455?
If the cap was loose, yes. It can take several days of normal driving before the EVAP monitor re-runs and the light goes off.
Is P0455 serious?
Not for the engine. It is an emissions fault, and you may smell fuel. It will fail an emissions test.
What is the difference between P0455 and P0442?
P0455 is a large leak, like a missing cap. P0442 is a small leak (about 0.040 inch), like a cracked hose or a worn cap seal.
What does P0455 mean?
P0455 stands for "Evaporative Emission System Leak Detected (Large Leak)". During a self-test, the computer seals the EVAP system and checks whether it can hold vacuum or pressure.
Can I drive with a P0455 code?
Safe to drive. It will fail an emissions test until fixed.
How much does it cost to fix P0455?
It depends on the cause. The likely repairs for P0455 range from about $15 to $700 at an independent shop in the US, plus a diagnostic fee of roughly $100-$200. These are rough estimates; dealer prices and some vehicles run higher.