What is the P0086 fault code?
The generic OBD-II code P0086 indicates a high value issue in the exhaust valve control solenoid circuit, bank 2. This fault, related to variable valve timing (VVT), affects vehicles of all makes (from 1996 onwards). The engine control module (ECM/PCM) detects an abnormally high voltage in the exhaust VVT control solenoid circuit on the bank 2 side (which does not contain cylinder number 1).
Symptoms of the P0086 code
When this fault code is stored, you may observe:
- The malfunction indicator lamp (MIL) is illuminated on the dashboard.
- Poor acceleration and engine hesitation.
- Increased fuel consumption.
- Irregular idle.
- Possibility of entering limp mode.
Possible causes of the P0086 fault
Several components can be the source of this problem:
- A faulty exhaust VVT control solenoid (bank 2).
- A wiring problem: open circuit, short to ground or power, corroded or loose connectors.
- Insufficient engine oil level or pressure.
- Degraded or poor-quality engine oil.
- A faulty engine control module (ECM/PCM) (less common).
Diagnostic procedure for the P0086 code
⚠️ Warning: These steps are generic. Always consult the technical documentation specific to your vehicle.
1. Preliminary checks
- Check the engine oil level and condition. Dirty oil or a low level can prevent the proper operation of the VVT system.
- Visually inspect the connectors and wiring of the VVT solenoid (bank 2) for any signs of damage, corrosion, or poor connection.
2. VVT solenoid test
- Disconnect the electrical connector from the solenoid.
- Using a digital multimeter (DVOM) in ohmmeter (Ω) mode, measure the resistance between the terminals of the solenoid.
- Compare the measured value to the manufacturer’s specifications. An infinite resistance (open circuit) or zero resistance (short circuit) indicates a faulty solenoid.
3. Electrical circuit test
- Using a wiring diagram, check for the absence of a short to ground or to power on the wires connecting the solenoid to the PCM.
- Check the wire continuity to ensure there is no open circuit.
4. Control and signal test
- Using an advanced diagnostic tool, activate the solenoid and check its operation (an audible click should be heard).
- Use an oscilloscope to analyze the PWM (Pulse Width Modulated) signal sent by the PCM and verify that it matches the commands displayed on the diagnostic tool.
5. PCM verification
If all other components are compliant, an internal fault in the engine control module (PCM) is possible, although rare.
Repair and advice
After identifying and correcting the cause of the P0086 fault, clear the codes using your diagnostic scanner. Perform a road test to verify that the fault does not reappear.
For complex VVT system issues, it is highly recommended to consult a professional mechanic with the necessary tools and expertise for an accurate diagnosis.
Need help diagnosing your vehicle? Consult a partner garage or invest in a reliable diagnostic tool to analyze your engine’s fault codes yourself.