P0449
Evaporative Emission System Vent Valve/Solenoid Circuit
Low· Fix when convenientDIY friendlyPowertrainGeneric, all makes
What it means
The evaporative emission (EVAP) system traps fuel vapour from the tank in a charcoal canister and later burns it in the engine. The ECU periodically seals the system and checks that it holds pressure or vacuum. The ECU has detected an electrical fault in the vent valve solenoid circuit.
Is it safe to drive?
Safe to drive. The EVAP system only handles fuel vapour, so it does not affect how the car runs, but the car will fail an emissions test and you may smell fuel.
Symptoms
- Check engine light on
Probable causes
Most likely first
- 1Failed vent solenoid
- 2Corroded connector (it sits under the car and gets wet)
- 3Open or shorted wiring
How to diagnose it
Work through these in order before buying parts
- 1Record the code and its freeze frame data (speed, load, temperature when it set), then clear it and see if it comes back.
- 2Inspect the connector for corrosion.
- 3Check the solenoid resistance and voltage supply.
- 4Check for technical service bulletins (TSBs) or software updates for your make and model; some codes have known factory fixes.
Common fixes
- Replace the vent solenoid
- Repair the connector or wiring
This information is general guidance for all makes. Exact causes, specifications and procedures vary by vehicle, so confirm with your service manual or a qualified mechanic before replacing parts.