The OBD2 code P0079 signifies “Exhaust Valve Control Solenoid Circuit Low Bank 1,” indicating that the circuit voltage for the exhaust valve control solenoid is below the expected range. This solenoid plays a pivotal role in managing the exhaust valves’ timing, essential for optimal engine performance.
Low voltage in this circuit can lead to engine issues such as hesitation during acceleration, rough idling, and even stalling.
P0079 quick overview
| Meaning | P0079: Exhaust Valve Control Solenoid Circuit Low Bank 1 |
| Is it serious? | Yes, it can lead to poor vehicle performance, increased emissions, and potentially cause the engine to stall. |
| Possible causes | – Faulty exhaust valve control solenoid – Damaged or corroded wiring harness – Poor electrical connections – Issues with the ECM |
| How to diagnose? | Inspect wiring harness for signs of damage or breaks. Test continuity and resistance along the circuit. Verify proper voltage supply to the solenoid. Check throttle body for any obstructions and proper operation. Verify ECM grounds and proper grounding of the solenoid. |
P0079 Meaning
When you see the P0079 code, your car is essentially telling you there’s a problem with the electrical signal going to the part that helps control the exhaust after the engine burns fuel. This can make your car feel sluggish, or it might not run as smoothly as it should.
The issue often lies within the wires and connections that send signals to this component. Fixing it usually involves finding and repairing any damaged wires or ensuring the component is properly connected and receiving the power it needs to function correctly.
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How to fix P0079 – learn from mechanics
I looked into P0079 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.
Case #1: Ford P0079
Vehicle information
Ford Mustang, 2016, 5.0L engine
Issue + repair history
- Check engine light flashing
- Replaced exhaust valve control solenoid
- Replaced throttle position sensor
- Car hesitates during acceleration
Other OBD2 Codes + Test Results
- P0079: Exhaust Valve Control Solenoid Circuit Low B1
- P0121: Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem
- Live data shows low voltage at the solenoid
Mechanic suggestions
- Inspect wiring harness for any signs of damage or breaks
- Test continuity and resistance along the circuit
- Verify proper voltage supply to the solenoid
- Check throttle body for any obstructions
Final fix
Found a loose connector at the exhaust valve control solenoid. Secured connector and cleared codes, issue resolved.
Case #2: Toyota P0079
Vehicle information
Toyota Camry, 2015, 2.5L engine
Issue + repair history
- Check engine light on intermittently
- Replaced exhaust valve control solenoid
- Replaced engine control module (ECM)
- No noticeable improvement
Other OBD2 Codes + Test Results
- P0079: Exhaust Valve Control Solenoid Circuit Low B1
- P0606: Control Module Internal Performance
- Test results indicate low voltage readings from the solenoid
Mechanic suggestions
- Inspect wiring harness for any signs of damage or wear
- Test continuity and resistance in the solenoid circuit
- Check for proper grounding of the solenoid
- Verify ECM grounds
Final fix
Discovered a damaged ground wire leading to the exhaust valve control solenoid. Repaired wire and cleared codes, issue resolved.
Case #3: BMW P0079
Vehicle information
BMW 3 Series, 2014, 2.0L engine
Issue + repair history
- Check engine light on constantly
- Replaced exhaust valve control solenoid
- Replaced engine coolant temperature sensor
- Vehicle experiencing rough idle and occasional stalling
Other OBD2 Codes + Test Results
- P0079: Exhaust Valve Control Solenoid Circuit Low B1
- P0118: Engine Coolant Temperature Sensor Circuit High Input
- Live data shows low voltage readings from the solenoid
Mechanic suggestions
- Inspect wiring harness for any signs of damage or corrosion
- Test continuity and resistance in the solenoid circuit
- Verify proper grounding of the solenoid
- Check for any restrictions in the exhaust system
Final fix
Discovered a damaged section of wiring harness near the exhaust valve control solenoid. Repaired wiring and cleared codes, issue resolved.
How to diagnose P0079
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Diagnostic Step | Brief Explanation |
|---|---|
| Inspect wiring harness and connectors | Look for physical damage or wear that could interfere with electrical signals. |
| Test continuity and resistance | Ensure that the electrical path is uninterrupted and components are within specification. |
| Verify proper voltage supply | Check if the solenoid is receiving sufficient voltage for operation. |
| Check throttle body and obstructions | Make sure there’s no blockage affecting airflow and sensor operation. |
| Verify ECM and solenoid grounding | Ensure the ECM and solenoid have a good ground connection to prevent electrical issues. |
| Secure loose connectors | Fix any detected loose connections to ensure stable electrical communication. |
| Inspect for restrictions in the exhaust system | Check if the exhaust flow is hindered, affecting engine performance. |
| Repair damaged ground wires | Fix any issues with ground wiring to ensure proper solenoid function. |
| Clear codes and perform test drive | After repairs, clear the diagnostic codes and test drive to ensure the issue is resolved. |
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko