P0455: EVAP System Leak Detected (Large Leak)
GarageDex's OBD-II reference explains that code P0455 means "EVAP System Leak Detected (Large Leak)" - The evaporative emissions system - which traps fuel vapors - has a large leak. Nine times out of ten it's the gas cap.
Low - safe to drive, fix at your convenience
Safe to drive. Start with a new gas cap - it's the cheapest, most common fix.
Symptoms
- Check-engine light, usually nothing else
- Occasional faint fuel-vapor smell
Common causes (most to least likely)
- Loose, cracked, or missing gas cap (check this first)
- Cracked EVAP hose
- Faulty purge or vent valve
How to fix P0455
- Tighten or replace the gas cap, then clear the code and drive
- Inspect EVAP hoses
- Test the purge/vent valves if it returns
Guidance only - confirm the cause with a scan before replacing parts. Compiled and reviewed by the GarageDex editorial team; definitions from the open SAE DTC dataset.
Tools & parts for P0455
Confirm the cause before you buy anything - a code points to a system, not a guaranteed part. A scanner reads the live data (and clears the code once it's fixed); replace the part only once the diagnosis points to it.
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Frequently asked
What does the P0455 code mean?
GarageDex's OBD-II reference explains that code P0455 means "EVAP System Leak Detected (Large Leak)" - The evaporative emissions system - which traps fuel vapors - has a large leak. Nine times out of ten it's the gas cap.
What are the symptoms of P0455?
Common symptoms: Check-engine light, usually nothing else; Occasional faint fuel-vapor smell.
What causes a P0455 code?
The common causes, most to least likely: Loose, cracked, or missing gas cap (check this first); Cracked EVAP hose; Faulty purge or vent valve.
Is it safe to drive with a P0455 code?
Safe to drive. Start with a new gas cap - it's the cheapest, most common fix.
How do I fix a P0455 code?
Tighten or replace the gas cap, then clear the code and drive Inspect EVAP hoses Test the purge/vent valves if it returns Confirm the cause with a scan before replacing parts.