P0446 means the ECU has detected a problem with the EVAP vent control circuit. The vent valve controls airflow through the charcoal canister that captures fuel vapours. When the valve or its circuit fails, the EVAP system cannot properly purge or seal, triggering this code.
DTC/P0446·BMW
P0446 on BMW: Causes, Symptoms and Fix Cost
Quick Answer
Low SeveritySafe to drive (short-term)BMW
P0446 on a BMW means the ECU has detected a problem with the EVAP vent control circuit. The vent valve controls airflow through the charcoal canister that captures fuel vapours. When the valve or its circuit fails, the EVAP system cannot properly purge or seal, triggering this code.
Repair cost on BMW€14 - €630
What does P0446 mean on a BMW?
BMW 3 Series
2006-2024BMW EVAP systems are more complex than most, with multiple valves and a fuel tank leak detection pump. P0446 on a BMW may also involve the leak detection pump or its associated wiring. The charcoal canister and vent valve are typically accessible from under the rear of the car. BMW-specific scan tools provide more detailed EVAP test results than generic OBD2 scanners.
What causes P0446 on a BMW?
Beyond the generic causes listed on the main P0446 page, these are the BMW-specific patterns we see most often:
BMW 3 SeriesLeak detection pump involvement in EVAP circuit on BMW
BMW 3 SeriesComplex multi-valve EVAP system requires BMW-specific diagnostics
How to diagnose P0446 on a BMW with OBD2
Follow these steps to pinpoint the root cause of P0446:
- Check gas cap for proper seal. Tighten and clear the code. If it returns, the cap is not the issue
- Locate the EVAP vent valve (usually near the charcoal canister, rear of vehicle or near fuel tank)
- Test vent valve with a scan tool: command it closed and listen for a click. No click means the solenoid has failed or has no power
- Check wiring and connector at the vent valve for corrosion, damage, or rodent chew marks
- Inspect the vent hose from canister to vent valve for kinks, cracks, or blockage
- Check the vent filter (if accessible) for debris or spider web blockage
How much does P0446 cost to fix on a BMW? (EUR)
Estimated repair costs on a BMW (BMW parts and labour typically run 40% above the average for this code).
Prices estimated as of May 2026. Costs vary by region, vehicle, and shop.
Related codes that often appear with P0446 on BMW
These codes commonly cluster with P0446 on BMW vehicles:
FAQ: P0446 on BMW
Can I drive with P0446?
Yes, completely safe. The EVAP system only controls fuel vapour emissions. No effect on engine performance or safety. You'll fail emissions testing though.
What is the EVAP vent valve?
A solenoid-controlled valve that allows fresh air into the charcoal canister during purge cycles. When the ECU tests the EVAP system for leaks, it closes the vent valve to seal the system. If it can't close or the circuit fails, P0446 is set.
Can a bad gas cap cause P0446?
Rarely. A bad gas cap more commonly triggers P0440 or P0455 (large leak). P0446 specifically points to the vent control circuit, not a general leak. But checking the cap first is free and takes 10 seconds.
How much does it cost to fix P0446?
The vent valve itself costs 30-120 euros. Labour is 40-150 euros since the valve is usually accessible near the rear of the vehicle. Total: 70-270 euros for most vehicles.
Looking for the full P0446 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0446 guideSkanyx · BMW
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