P0079
UniversalExhaust Valve Control Circuit Low (Bank 2)
The engine computer has detected a low electrical signal in the exhaust valve control circuit for Bank 2. That circuit controls an exhaust-valve-related system, and the code identifies an electrical condition—not proof that a valve or actuator has failed. The check-engine light may be the only noticeable effect, though some vehicles may also have changes in engine operation or emissions. Exact system design and diagnostic steps depend on the vehicle, year, and engine.
⚠️ Before You Begin (Safety First)
If the vehicle runs normally, this fault is not usually an immediate reason to stop driving, but arrange diagnosis soon. Stop safely and seek assistance if the engine stalls, runs very roughly, loses substantial power, or shows signs of overheating. Avoid touching hot exhaust components.
Common Symptoms
- The check-engine light may be on, with no other noticeable symptoms.
- Engine operation may be rough or performance may change if the controlled exhaust-valve system affects engine operation.
- Emissions or fuel economy may be affected, depending on the vehicle's system and how it responds to the fault.
Common Causes
- A damaged wire or short to ground may pull the control circuit signal low.
- A loose, corroded, wet, or damaged connector may interfere with the circuit.
- An exhaust valve control actuator or solenoid may have an internal electrical fault.
- A power, ground, or control-circuit problem may affect the signal.
- A control-module fault is possible but should be considered only after the circuit and component are tested.
Diagnostic Steps
- Note any drivability symptoms and check whether the check-engine light is steady or flashing; severe symptoms call for stopping safely and getting help.
- With the engine off and cool, visually inspect accessible wiring and connectors related to the Bank 2 exhaust valve control system for damage, looseness, corrosion, or contamination.
- Use a compatible scan tool to check for related codes and save available code and freeze-frame information before clearing anything.
- Compare findings with service information for the exact vehicle. Avoid probing terminals or replacing parts without the correct circuit details and test procedure.
When to Call a Professional
A technician can check for related codes and review scan data, inspect the Bank 2 circuit and connectors, and test the circuit and actuator using vehicle-specific service information. The low signal may result from wiring, a connector, the controlled component, or its control circuit; verify the cause before replacing parts.
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Commonly Asked Questions
Does P0079 prove the exhaust valve actuator is bad?
No. It reports a low signal in the Bank 2 exhaust valve control circuit. Wiring, a connector, the controlled component, or another circuit fault can cause that condition.
Does “circuit low” mean the exhaust valve is stuck open or closed?
Not by itself. The code describes an electrical signal condition, not a confirmed valve position or mechanical failure.
Can I keep driving with P0079?
If the vehicle runs normally, driving to arrange diagnosis may be reasonable. Stop safely if it stalls, runs very roughly, loses substantial power, or shows signs of overheating.
Why does the exact vehicle matter for diagnosis?
The exhaust valve control system, circuit layout, and test procedure can vary by model, year, and engine. Vehicle-specific service information is needed to identify the correct component and checks.
Related Diagnostic Video
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