Emissions

P0449 — EVAP Vent Valve/Solenoid Circuit Malfunction

Severity: low Safe to drive

What P0449 means

P0449 means the engine control module detected an electrical problem in the circuit of the EVAP vent valve solenoid. Normally this valve opens to let fresh air into the charcoal canister while fuel vapors are purged, and closes during system leak tests. If the control signal or voltage in the circuit is not what the module expects, it sets the code and turns on the check engine light.

Symptoms

  • Check engine light is on
  • Faint fuel vapor smell near the vehicle
  • Failed emissions test
  • Fuel pump nozzle clicking off repeatedly while refueling
  • Stronger fuel smell if there is also a leak

Possible causes

  1. Faulty EVAP vent valve (solenoid)
  2. Damaged wiring or corroded connector at the vent valve
  3. Open or short in the vent valve control circuit
  4. Blown fuse for the vent valve circuit
  5. Faulty driver inside the PCM (uncommon)
  6. Contaminated or damaged charcoal canister

How to diagnose

  1. Scan for codes and freeze frame data, clear the code and see if it returns
  2. Check that the fuel cap is seated properly and its seal is intact
  3. Inspect the vent valve connector and harness for damage, corrosion and water intrusion
  4. Check the fuse for the vent valve circuit
  5. Measure the solenoid coil resistance and compare it to specifications
  6. Command the vent valve on with a scan tool and confirm it clicks and changes state
  7. Check for power and control signal at the connector, and test the wiring to the PCM for opens and shorts
  8. Read fuel tank pressure sensor data and smoke-test the EVAP system if needed

Common fixes

  • Replace the EVAP vent valve
  • Repair damaged wiring or replace the connector
  • Replace the blown fuse and fix the cause of the short
  • Replace the charcoal canister if contaminated or damaged
  • Replace or reprogram the PCM if it is confirmed faulty

Questions and answers

What does code P0449 mean?

The engine computer found an electrical fault in the circuit of the EVAP vent valve. The cause may be the valve itself, wiring, a connector or a fuse.

Can I drive with P0449?

Usually yes, because it rarely affects how the engine runs. Don't put the repair off too long, though, as you may get a fuel smell, refueling problems or a failed emissions inspection.

Can a loose gas cap cause P0449?

A loose cap more often sets EVAP leak codes than an electrical circuit code. It is still worth checking first to rule out other problems.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.