P0079 - Exhaust Valve Control Solenoid Circuit Low (Bank 1)
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P0079 is a generic diagnostic trouble code (DTC) indicating that the Engine Control Module (ECM) has detected an unexpectedly low voltage in the exhaust valve control solenoid circuit (for Variable Valve Timing - VVT) on Bank 1. The ECM uses Pulse Width Modulation (PWM) to control the solenoid. If the ECM attempts to command the solenoid 'ON' but detects a voltage below the calibrated threshold (typically near 0V when it should be high), this code is triggered. This usually signifies a short to ground or an open circuit in the solenoid or wiring.
Possible Causes
Faulty VVT solenoid (internal short/open circuit)
Damaged wiring (short to ground in the signal wire)
Blown fuse providing power to the solenoid/control circuit
Internal ECM/ECU failure
Symptoms
Recommended Solution
Workflow
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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