P0499 High signal level in the control circuit of the ventilation valve of the EVAP system

P0499 – OBD-II Trouble Code Technical Description

Trouble code P0499 indicates that the ECM (engine control module) has detected too high a voltage in the evaporative emission control valve control circuit.

What does the fault code mean P0499?

Trouble code P0499 indicates that the engine control module (ECM) has detected too high voltage in the evaporative emission control valve control circuit. This means that the permissible voltage in the ventilation valve control system has been exceeded, which can lead to improper operation of the fuel vapor recovery system. The fuel vapor recovery system is designed to prevent fuel vapor from leaking into the atmosphere. At a certain point, the evaporative emission system purge valve opens and introduces fresh air into the system. If the vehicle's PCM detects too high voltage in the evaporative emission control valve control circuit, a P0499 code will appear.

Possible reasons

Some possible reasons for the P0499 trouble code:

• Problem with the evaporative evacuation system vent valve: Problems with the valve itself can cause the evaporative emission system to not operate properly and cause the P0499 code to appear.
• Damaged or Broken Wires: The wires connecting the vent valve to the engine control module may be damaged or broken, causing the circuit to have incorrect voltage and triggering the P0499 code.
• Faulty Engine Control Module (ECM): If the vehicle's ECM is not functioning properly, it can cause the ventilation valve to not control properly and result in a P0499 code.
• Electrical System Problems: The voltage in the vent valve control circuit may be lost due to problems with the vehicle's electrical system, such as a short circuit or electrical overload.
• Other mechanical problems: Some other mechanical problems, such as evaporative emission system leaks or a clogged vent valve, can also cause P0499.

What are the symptoms of a fault code? P0499?

Some possible symptoms when trouble code P0499 appears:

• Check Engine Light Illuminated: When P0499 appears, the Check Engine light on the instrument panel will turn on.
• Increased fuel consumption: Improper operation of the evaporative emission system vent valve can result in increased fuel consumption due to improper operation of the evaporative treatment system.
• Loss of Power: In some cases, especially if the problem is severe, a loss of engine power may occur due to improper operation of the evaporative emission control system.
• Engine Irregularity: Irregular engine speed or rough operation may be the result of a malfunction in the evaporative emission system.
• Fuel Odor: If fuel vapors from the evaporative emission system are leaking into the atmosphere, you may notice a fuel odor around the vehicle.

How to diagnose a fault code P0499?

To diagnose and resolve the problem associated with DTC P0499, we recommend the following steps:

1. Check the evaporative emission system: Check the condition of all components of the evaporative emission system, including the vent valve, lines, and charcoal canister. Make sure there are no leaks, damage or blockages.
2. Check electrical connections: Check the electrical connections in the ventilation valve control circuit. Make sure all connections are secure and free of corrosion.
3. Use an OBD-II scan: Connect an OBD-II scanner to your vehicle's diagnostic port and perform a scan to check for other trouble codes and get detailed information about the status of the evaporative emission system.
4. Check the fuel vapor pressure sensor: Check the fuel vapor pressure sensor for functionality. Make sure it reads the fuel vapor pressure correctly and sends the appropriate signals to the ECM.
5. Check Vacuum Hoses: Check the condition of all vacuum hoses connected to the evaporative emission system. Make sure they are not cracked, pulled or leaking.
6. Check the vent valve: Check the evaporative emission system vent valve for proper operation. Replace it if necessary.
7. Check fuel pressure: Check the fuel pressure in the evaporative emission system. Make sure it meets the manufacturer's specifications.
8. Check the fuel gauge: Check the fuel gauge for proper operation. Make sure it correctly reads the fuel level in the tank and sends appropriate signals to the ECM.

Diagnostic errors

When diagnosing DTC P0499, the following errors may occur:

• Sensor malfunction: One error may be incorrect interpretation of signals from the fuel vapor pressure sensor or fuel sensor. This may lead to the problem being misdiagnosed or unnecessary components being replaced.
• Insufficient System Testing: Some errors may occur due to incomplete or insufficient testing of the entire evaporative emission control system. Incorrect identification of the cause may result in incorrect replacement of components.
• Misinterpretation of data: The error may be due to misinterpretation of data received from the OBD-II scanner or other diagnostic equipment. Misunderstanding of data may lead to incorrect diagnosis.
• Electrical connection problems: If there is no physical damage to the system components but the problem still persists, it may be due to faulty or unreliable electrical connections. Insufficient checking of electrical connections may lead to incorrect diagnosis.

How serious is the fault code? P0499?

Trouble code P0499, which indicates that the evaporative emission control valve control circuit voltage is too high, is serious because it may cause the evaporative emission control system to malfunction. Although not safety critical, the error can result in fuel vapors escaping into the atmosphere, which not only can result in negative environmental impacts, but also impair fuel economy and engine performance. Therefore, it is recommended that you take steps to fix this problem as soon as possible.

What repair will help eliminate the code? P0499?

To resolve DTC P0499, the following repair steps are recommended:

1. Check the electrical circuit: Check the wires and connectors connecting the evaporative emission control valve to the engine control module (ECM). Make sure there are no breaks, corrosion or other damage.
2. Check the vent valve: Check the evaporative emission system vent valve itself for proper operation. It may be blocked or not closing properly.
3. Check the valve position sensor: Check the evaporative emission control valve position sensor. It may be damaged or malfunctioning, resulting in erroneous ECM signals.
4. Check circuit voltage: Measure the voltage at the evaporative emission control valve control circuit using a multimeter. Make sure the voltage is within acceptable limits.
5. Component Replacement: If necessary, replace damaged or failed components, such as the vent valve or valve position sensor.
6. Check ECM Software: Sometimes the problem may be related to the ECM software. Update or reprogram the ECM if necessary.

After completing these steps, the P0499 trouble code will clear, then take it for a test drive to ensure that the problem has been successfully resolved.

What is P0499 Engine Code [Quick Guide]

P0499 – Brand-specific information

Trouble code P0499 can be found in various brands of cars, some of them with explanations:

1. Audi: Problem with the evaporative emission system vent valve.
2. BMW: Low voltage in the evaporative emission system ventilation valve control circuit.
3. Chevrolet: The voltage in the evaporative emission control valve control circuit is too high.
4. Ford: Excessive voltage in the control circuit of the ventilation valve of the fuel vapor recovery system.
5. Honda: Low voltage in the evaporative emission system ventilation valve control circuit.
6. Toyota: Problem with the evaporative emission system vent valve.
7. Volkswagen: The evaporative emission control valve control circuit voltage is too low.

Please note that the interpretation of fault codes may vary slightly depending on the model and year of the vehicle. It is always recommended to consult the official repair and service manual for your specific vehicle make and model.