Exhaust Valve Control Solenoid Circuit Low (Bank 1)
The P0079 code indicates that the Powertrain Control Module (PCM) has detected a low voltage condition in the exhaust valve control solenoid circuit for Bank 1. This solenoid is part of the variable valve timing (VVT) system, which adjusts exhaust valve timing to optimize engine performance and emissions. A low circuit voltage suggests a short to ground, open circuit, or faulty solenoid, potentially causing poor engine performance and increased emissions.
01. Most Common Causes
- Faulty exhaust valve control solenoid
- Short to ground in the solenoid circuit
- Open circuit or damaged wiring/connector
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or hesitation
- Rough idle or stalling
- Decreased fuel economy
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm P0079 and check for other codes.
Step 2: Visually inspect the exhaust valve control solenoid and its wiring for damage or corrosion.
Step 3: Test the solenoid resistance with a multimeter; compare to manufacturer specs (typically 10-20 ohms).
Step 4: Check for voltage at the solenoid connector with the engine running; should be battery voltage.
Step 5: If voltage is low, trace circuit for shorts or opens; repair as needed.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as it can cause poor engine performance and potential damage to the catalytic converter.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, including parts and labor, depending on the cause and vehicle make.