What does code P0446 mean on a Mercedes-Benz and is it safe to drive?
P0446: Evaporative Emission System Vent Control Circuit. Here's what it means on your Mercedes-Benz, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
What this code means
The PCM has detected a problem with the EVAP vent control circuit, often caused by a stuck or failed vent valve.
Common causes for your Mercedes-Benz
- Failed EVAP vent solenoid
- Corroded wiring or connector at vent valve
- Blocked vent due to dust, rust, or spider webs
Symptoms
- Check Engine Light
- Possible difficulty filling fuel tank (nozzle keeps clicking off)
Typical fixes
- Replace EVAP vent valve/solenoid
- Clean or clear vent and charcoal canister area
- Repair wiring
Repair cost range
For a Mercedes-Benz, repairs for P0446 often fall between $150 and $450, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on Mercedes-Benz
Mercedes P0446 EVAP vent control fault typically involves the carbon canister vent solenoid or the leak detection pump. Use XENTRY diagnostics to command the vent valve before replacing parts—Mercedes EVAP system faults often require dealer-level diagnostics to properly isolate.
Most commonly affected models