What does the P0079 code mean?
The P0079 trouble code, applicable to all car manufacturers, means “Exhaust Valve Control Solenoid Circuit Low (Bank 1)“.
Background Information: The camshaft controls the opening and closing of the valves. In a variable valve timing system, the electronic camshaft actuator (or oil control valve, OCV) adjusts the camshaft angle by changing the oil pressure to the camshaft adjuster (mechanical) based on commands from the engine control module (ECM), ensuring the valves open and close at the optimal time. This fault code appears if the exhaust camshaft actuator circuit voltage is below the calibrated minimum value.
Symptoms of Error Code P0079
- Unstable engine idle
- Reduced engine power
- Increased fuel consumption
- Delayed response when pressing the accelerator
- Check engine light on the dashboard
Main Causes of Error Code P0079
- Faulty VVT solenoid valve
- Open or short circuit in the wiring
- Oxidation or contamination of the connector
- Engine control unit failure (rare)
How to diagnose error code P0079?
- Use an OBD2 diagnostic scanner to read the error code
- Clear the fault code and test the vehicle
- Check the voltage of the VVT solenoid valve connector (usually 12V when activated)
- Perform a valve resistance test (usually 6-12 ohms)
- Check the wiring and connectors for damage or corrosion
Possible Causes and Diagnostic Methods
| Possible Cause | How to check? |
|---|---|
| Faulty VVT valve | Check the valve’s resistance, power, and response |
| Damaged wiring | Check the wiring harness, check the integrity of the cables |
| Poor connector contact | Check for corrosion, clean the contacts |
| Problem with the ECM control unit | Diagnose with an OBD2 scanner |
Tools needed: OBD2 scanner, multimeter, automotive tool kit, contact cleaner
How to fix error code P0079? (Solutions to the problem)
Simple repair methods
- Clean the VVT valve connector contacts
- Replace damaged fuses
- Reset the error code after verification
In-depth diagnostic and repair solutions
- Replace the faulty timing phase control valve
- Repair or replace damaged wiring
- Replace or reflash or replace the ECM if necessary.
Troubleshooting Through Symptoms
| Symptoms | Possible Solutions |
|---|---|
| Unstable engine operation | Check and replace the VVT valve |
| Check the engine | OBD2 diagnostics and troubleshooting |
| Poor traction and fuel consumption | Cleaning/repairing contact points and wiring |
Common Vehicle Error Code P0079
P0079 in BMW: In BMWs, the error may be due to a contaminated VVT valve, especially with irregular oil changes.
P0079 in Honda: In Honda models, this occurs when the connector is worn and the wiring in the timing area is aging.
P0079 in Hyundai: It may be caused by motor overheating, which in turn affects the stability of the valve power supply circuit.
P0079 in Toyota: The error occurs due to a failure of the phase change solenoid valve, especially after exceeding 150,000 kilometers.
P0079 in Chevrolet: This is usually caused by contact corrosion and contamination of the VVT oil passages.
P0079 Frequently Asked Questions
Can you drive with error code P0079?
Not recommended. The error can lead to unstable engine operation, loss of power, and increased fuel consumption.
What does low voltage in the VVT circuit mean?
It means that the engine control module detects insufficient voltage supplied to the valve solenoid to change the valve timing, which may be due to an open circuit, short circuit, or valve malfunction.
Can you reset error code P0079 yourself?
Yes, using an OBD2 scanner or temporarily disconnecting the battery. However, if the problem persists, the error will reappear.
Does error P0079 require replacing the VVT valve?
Not necessarily. Sometimes cleaning the contacts or replacing the wiring is sufficient. But if there is mechanical wear, the valve must be replaced.
Does error P0079 affect fuel consumption?
Yes, if the VVT system malfunctions, the fuel mixture combustion efficiency decreases, thus increasing fuel consumption.
P0079 Related OBD2 Errors
P0010 – A Camshaft Position Actuator Circuit/Open (Bank 1)
P0078 – Exhaust Valve Control Solenoid Circuit (Bank 1)
P0080 – Exhaust Valve Control Solenoid Circuit High (Bank 1)
Important! Ignoring error P0079 may lead to decreased engine performance and damage to other components of the VVT system. Regularly changing the engine oil and checking electrical connections can help prevent this error from occurring again in the future.