P0449 on a Mercedes-Benz: Causes, Fixes & Repair Cost
🟢 Low severity · drivable
Safe to drive — this is an emissions-system electrical fault — but fix it before an emissions test or a fuel smell appears.
What P0449 means on a Mercedes-Benz
On a Mercedes-Benz, P0449 means the engine computer sees an electrical fault in the circuit for the EVAP vent valve near the fuel tank. The valve opens to let fresh air into the vapor canister during a purge, and a corroded connector or failing valve sets the code.
Is P0449 common on Mercedes-Benzs?
P0449 appears on Mercedes-Benz C-Class, E-Class, and ML-Class models as the vent valve or its wiring ages. The connector and the valve itself are the usual failure points on this brand, similar to other EVAP codes.
Commonly reported on: C-Class, E-Class, ML-Class, GL-Class.
Symptoms
- Check engine light is on
- Possible faint fuel smell
- No change in how the car drives
Common causes
- most common: Corroded or loose vent valve connector
- common: Faulty vent valve
- common: Chafed or damaged wiring to the valve
- less common: Faulty EVAP canister or vent valve assembly
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Clean and reseat the vent valve connector | Yes | $0–30 |
| Repair chafed or corroded wiring | Yes | $40–150 |
| Replace the vent valve | Mechanic | $150–400 |
Frequently asked questions
Other common Mercedes-Benz codes
P0449 on other brands
Looking for the full (non-brand-specific) guide? See the P0449 code page →
Browse all Mercedes-Benz codes: Mercedes-Benz hub →
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.