P0079 Code – Exhaust Valve Control Solenoid Circuit Low

What Does the P0079 Code Mean

The P0079 diagnostic trouble code (DTC) indicates that the engine control unit (ECU) has detected a low voltage condition in the exhaust valve control solenoid circuit on bank 1.

The exhaust valve control solenoid is part of the Variable Valve Timing (VVT) system. This system allows the engine to adjust the timing of the exhaust valves depending on engine speed and load.

The solenoid controls the flow of engine oil to the camshaft actuator, which adjusts the position of the exhaust camshaft. This improves:

• engine efficiency

• fuel economy

• power output

• emissions performance

If the ECU detects that the voltage in the solenoid circuit is lower than the expected range, it will trigger the P0079 OBD2 code.

This usually indicates a short to ground, wiring damage, or a failing solenoid.

Symptoms of Code P0079

Drivers may notice several symptoms, including:

• Check Engine light illuminated

• Rough idle

• Reduced engine performance

• Hesitation during acceleration

• Increased fuel consumption

• Possible engine stalling in severe cases

Some vehicles may also experience irregular valve timing operation.

Common Causes of P0079

Typical causes include:

• Faulty exhaust valve control solenoid

• Short circuit to ground in the wiring

• Damaged wiring harness

• Loose or corroded electrical connectors

• Low or contaminated engine oil

• Faulty ECU driver circuit

Because the VVT system depends on clean engine oil and proper oil pressure, poor oil maintenance can contribute to this issue.

How Serious Is Code P0079

The P0079 code is considered a moderate severity problem.

The vehicle may still be drivable, but ignoring the issue may lead to:

• poor engine performance

• increased fuel consumption

• incorrect valve timing

• additional engine trouble codes

Repairing the issue early helps maintain proper engine operation.

How to Diagnose Code P0079

Diagnosis typically involves the following steps:

1. Scan the vehicle with an OBD2 diagnostic scanner

2. Check live data related to VVT system operation

3. Inspect the exhaust valve control solenoid

4. Check wiring and electrical connectors

5. Test solenoid resistance using a multimeter

6. Verify ECU control signals

Technicians may also inspect engine oil level and quality, since VVT systems rely on proper lubrication.

How to Fix Code P0079

Possible repair solutions include:

• replacing the exhaust valve control solenoid

• repairing damaged wiring

• cleaning or replacing electrical connectors

• changing engine oil and oil filter

• clearing the fault code after repair

In many vehicles, replacing the solenoid resolves the issue.

Vehicles Commonly Affected by P0079

The P0079 trouble code may appear on vehicles equipped with variable valve timing systems, including:

• Toyota

• Nissan

• Honda

• Ford

• Volkswagen

• BMW

• Hyundai

Any modern engine using VVT technology can potentially trigger this code.

FAQ – P0079 Code

Can I drive with code P0079?

Yes, but engine performance may be reduced and fuel consumption may increase.

Can dirty engine oil trigger this code?

Yes. Dirty oil can interfere with VVT solenoid operation.

Is replacing the exhaust valve control solenoid expensive?

In most vehicles the solenoid is relatively affordable and not difficult to replace.

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P0079 code

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P0079 code indicates a low voltage condition in the exhaust valve control solenoid circuit on bank 1. Learn the symptoms, causes and solutions for this OBD2 trouble code.