The P0499 trouble code indicates that the evaporative emission (EVAP) system has detected a high voltage condition in the vent valve control circuit. The vent valve controls the flow of vapors from the fuel tank to the charcoal canister, which stores them temporarily before they are purged into the engine for combustion. A high voltage condition in the vent valve control circuit can disrupt the proper operation of the EVAP system.
Evaporative Emission System Vent Valve Control Circuit High
Code symptoms P0499.
1. Illumination of the “Check Engine” or “Service Engine Soon” light on the dashboard.
2. Possible fuel odor around the vehicle, especially when parked or during refueling.
3. Reduced engine performance or drivability issues.
4. Increased emissions.
This code is common in brands such as:: Chevrolet, Renault, Ford, Toyota, Nissan, Mercedes Benz, Honda.
Causes of the code P0499.
1. Faulty evaporative emission vent valve.
2. Short to power in the vent valve control circuit.
3. Wiring or connector issues in the vent valve control circuit.
4. Corrosion or poor electrical connections in the vent valve control circuit.
5. ECM (Engine Control Module) software issues.
Code Solutions P0499.
1. Test the evaporative emission vent valve for proper operation. Replace the vent valve if it is faulty.
2. Check for a short to power in the vent valve control circuit. Repair any short circuits as necessary.
3. Inspect the wiring and connectors in the vent valve control circuit for damage, corrosion, or loose connections. Repair or replace any damaged components as needed.
4. Check for any corrosion or poor electrical connections in the vent valve control circuit. Clean or repair as necessary.
5. Ensure that the ECM software is up-to-date. If necessary, reflash or update the ECM software to the latest version.
6. Clear the trouble codes and perform a test drive to verify that the issue has been resolved.
7. If the problem persists, further diagnosis may be needed to identify the root cause of the issue. Consulting a qualified mechanic or performing additional tests using diagnostic equipment may be necessary.