EVAP System Gross Leak Detected
Code P0455 indicates a major leak in the evaporative emission control (EVAP) system, which prevents fuel vapors from escaping into the atmosphere. The system is designed to capture and store fuel vapors from the fuel tank and purge them into the engine for combustion. A gross leak means the system cannot hold pressure, often due to a loose or missing gas cap, a cracked hose, or a faulty purge valve. This triggers the check engine light and may cause a slight fuel smell.
01. Most Common Causes
- Loose, damaged, or missing gas cap
- Cracked or disconnected EVAP hoses
- Faulty purge valve stuck open
- Damaged charcoal canister
- Leaking fuel tank or filler neck
02. Symptoms You Will Notice
- Check engine light illuminated
- Fuel odor near the vehicle
- Possible slight decrease in fuel economy
03. Step-by-Step Diagnosis
Step 1: Inspect and tighten the gas cap; clear the code and retest.
Step 2: Perform a smoke test on the EVAP system to locate the leak.
Step 3: Check EVAP hoses, purge valve, and canister for damage.
Step 4: Repair or replace the faulty component and clear the code.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, it is generally safe to drive, but the check engine light will stay on. The main concern is fuel vapor escaping, which can cause a slight fuel smell and may fail an emissions test.
How much does it cost to fix?▼
If it's just a loose gas cap, it's free. Otherwise, repair costs range from $50 to $150 for a new gas cap or hose, up to $300-$500 if the purge valve or canister needs replacement.