What Does P0079 Mean?
This code indicates the ECM has detected a low voltage or short-to-ground condition on the exhaust VVT oil control solenoid circuit for bank 1. The solenoid control signal is being pulled low, preventing proper modulation of exhaust valve timing. The exhaust camshaft may be stuck at maximum retard or default position, reducing exhaust scavenging efficiency and causing rough idle and increased emissions.
Common Causes
35%
Short-to-ground in the exhaust VVT solenoid control wiring due to insulation breakdown from exhaust heat exposure
30%
Internally shorted exhaust VVT solenoid coil measuring below 6.5 ohms resistance
20%
Water intrusion or corrosion in the solenoid connector causing current leakage to ground
15%
ECM low-side driver circuit malfunction holding the control line low
Diagnostic Steps
1
Disconnect the exhaust VVT solenoid and measure coil resistance. A reading below 6.5 ohms indicates an internal short circuit requiring solenoid replacement.
2
With the solenoid disconnected, measure resistance from the control wire at the harness connector to a known good engine ground. Near 0 ohms confirms a short-to-ground in the wiring.
3
Inspect the exhaust VVT solenoid wiring for heat damage, particularly where the harness routes near the exhaust manifold or catalytic converter. Check for melted conduit or bare copper.
4
If the wiring tests normal, reconnect the solenoid and backprobe the ECM control pin. With ignition on and engine off, voltage should be near 12V. A low voltage reading with the solenoid disconnected indicates an ECM driver fault.
5
After repair, clear codes and verify exhaust cam timing responds correctly to duty cycle commands via the scan tool.
Estimated Repair Cost
$75 - $350
Parts + labor, varies by vehicle and location
This code indicates the ECM has detected a low voltage or short-to-ground condition on the exhaust VVT oil control solenoid circuit for bank 1. The solenoid control signal is being pulled low, preventing proper modulation of exhaust valve timing. The exhaust camshaft may be stuck at maximum retard o...
The most common cause of P0079 (Exhaust Valve Control Solenoid Circuit Low (Bank 1)) is: Short-to-ground in the exhaust VVT solenoid control wiring due to insulation breakdown from exhaust heat exposure
Typical repair costs for P0079 range from $75 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This condition primarily affects engine efficiency and emissions. The vehicle remains drivable but may have reduced power, which could affect acceleration during highway merging.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0079 to identify the root cause.
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Quick Info
Category
Powertrain
System
Variable Valve Timing (VVT) System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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