P0079 moderate

Exhaust Valve Control Solenoid Circuit Low (Bank 1)

The P0079 code means the vehicle's onboard diagnostic system has detected: Exhaust Valve Control Solenoid Circuit Low (Bank 1). This is a moderate severity code.

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Keep driving?: Short distances only
DIY difficulty: hard
Estimated cost: $80 - $450 (parts and labor)

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Common Symptoms

Check Engine Light illuminated
Rough or unstable idle
Decreased engine power
Poor fuel economy

Probable Causes (Ranked by Likelihood)

Short to ground in exhaust VVT solenoid circuit Very High
Internally shorted exhaust VVT solenoid High
Wiring harness chafed against exhaust components Moderate
PCM output driver shorted Low

Step-by-Step Diagnostic Procedure

Measure exhaust VVT solenoid resistance. Below 5 ohms suggests an internal short.
Inspect the wiring harness carefully where it passes near exhaust manifold or downpipe for heat damage.
Disconnect the solenoid and check for a short to ground on the harness side with a multimeter.
Test PCM driver output with solenoid disconnected. Voltage should toggle on command.

Frequently Asked Questions

What causes a low circuit on the exhaust VVT solenoid?

A low circuit is typically caused by a short to ground in the wiring or an internally shorted solenoid coil. Heat damage from nearby exhaust components is a common cause.

How do I find a short in the VVT wiring?

Visually inspect the harness for melted insulation or chafing, especially near exhaust components. Use a multimeter to check for continuity between each wire and ground with the solenoid disconnected.

Can heat damage the VVT solenoid wiring?

Yes, the exhaust VVT solenoid wiring runs close to hot exhaust components. Over time, heat can melt or crack wire insulation, causing shorts to ground.