Damaged or disconnected wiring or connector at the cylinder 10 exhaust valve actuator; Failed exhaust valve control solenoid or actuator; Corroded or loose electrical terminals in the circuit; Open or short to ground in the control circuit wiring; Faulty powertrain control module (PCM) driver circuit (less common); Exhaust valve mechanically stuck, causing the actuator to draw abnormal current

DTC codes / P34xx · Auxiliary emission controls / P3479

P3479Cylinder 10 Exhaust Valve Control Circuit Low

Q: What does code P3479 mean?

Cylinder 10 Exhaust Valve Control Circuit Low. P3479 indicates that the powertrain control module (PCM) has detected a low-voltage condition on the electrical circuit that controls the exhaust valve for cylinder 10. This circuit typically operates a solenoid or actuator that adjusts exhaust flow, and a low signal means the PCM sees voltage below the expected range, which can prevent the valve from functioning correctly.

P3479 indicates that the powertrain control module (PCM) has detected a low-voltage condition on the electrical circuit that controls the exhaust valve for cylinder 10. This circuit typically operates a solenoid or actuator that adjusts exhaust flow, and a low signal means the PCM sees voltage below the expected range, which can prevent the valve from functioning correctly.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaAuxiliary emission controls

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Rough idle or misfire-like behavior, especially under light load
Reduced engine performance or power output
Increased exhaust noise or a change in exhaust tone
Poor fuel economy in some cases
In rare instances, the engine may enter limp mode

Common causes, most likely first

Damaged or disconnected wiring or connector at the cylinder 10 exhaust valve actuator
Failed exhaust valve control solenoid or actuator
Corroded or loose electrical terminals in the circuit
Open or short to ground in the control circuit wiring
Faulty powertrain control module (PCM) driver circuit (less common)
Exhaust valve mechanically stuck, causing the actuator to draw abnormal current

How to diagnose and fix it

Inspect the wiring harness and connector at the cylinder 10 exhaust valve actuator for damage, corrosion, or looseness
Measure resistance of the exhaust valve control solenoid and compare to manufacturer specifications
Check for voltage and ground signals at the actuator connector with the key on and engine off
Test the control circuit for continuity and shorts to ground using a digital multimeter
If the circuit tests good, command the actuator with a scan tool to verify operation and listen for clicking or movement
Replace the faulty exhaust valve actuator or solenoid if it fails electrical or functional tests
Clear the diagnostic trouble code and verify the repair with a test drive

What most technicians overlook on P3479

A low-voltage code often results from a poor ground connection rather than a failed actuator, so always check ground points before replacing parts.
The exhaust valve control circuit may share power or ground with other circuits, so a fault elsewhere can trigger this code without any issue in the cylinder 10 circuit itself.
In some vehicles, the exhaust valve is part of a variable valve timing system, and a mechanical fault in the valve train can cause the actuator to report low voltage.
A scan tool that can graph the control circuit voltage in real time is invaluable for catching intermittent faults that do not appear during a simple resistance check.
After replacing an actuator, the PCM may require a relearn procedure to calibrate the new component, otherwise the code may return.

Can I keep driving with P3479?

You can generally drive the vehicle with this code, but avoid aggressive acceleration or heavy loads until it is repaired, as the exhaust valve may not function correctly and could affect engine performance or emissions.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.