Tracking P0455 on Your 2020 Mercedes-Benz C-Class
P0455 on your 2020 C-Class (W205) means a large EVAP leak. This final-year W205 with the 2.0L turbo or AMG engine may still be under warranty. Gas cap is the easiest fix to try first.
Symptoms
- Check engine light with P0455
- Fuel smell possible
- Gas cap worn
- Emissions test failure
Causes by Likelihood
- Gas Cap Seal (Very High Likelihood): Degraded after 4+ years. $15–$35.
- Leak Detection Pump (Medium Likelihood): Mercedes LDP failure. $280–$500 installed.
- EVAP Purge Valve (Medium Likelihood): Sticking. $200–$400 installed.
- Fuel Tank Vent Valve (Low-Medium Likelihood): Seal deterioration. $220–$420 installed.
- Vapor Hose (Low Likelihood): Age-related cracking. $120–$280.
Diagnosis
New gas cap first. If P0455 persists, XENTRY diagnostics at a Mercedes dealer or smoke testing at an independent shop will find the leak.
Warranty
Mercedes' 4yr/50k warranty may have expired. Federal emissions (8yr/80k) covers EVAP through 2028.
Safe to Drive?
Yes. P0455 is a vapor code. Engine, 9G-TRONIC, 4MATIC, and all systems work normally.