P0079

Exhaust Valve Control Circuit Low (Bank 2)

Powertrain Emission Controls Variable Valve Timing 🟡 Moderate — Fix within a week ⚠️ Drive with Care
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What This Actually Means

In plain language — no jargon

The engine computer detected that the exhaust valve control circuit on Bank 2 (the side of the engine opposite the #1 cylinder) is receiving too little electrical voltage. It's like a dimmer switch stuck too low—the valve isn't getting enough power to open and close properly.

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Symptoms You May Notice

3 known symptoms for this code
Check Engine Light illuminated
Rough idle or hesitation during acceleration
Increased emissions or failed emissions test
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECM monitors the voltage and current supplied to the Variable Valve Timing (VVT) solenoid on Bank 2's exhaust camshaft. When the measured voltage drops below the minimum threshold (typically 4.5–5.5V), the ECU logs a fault, indicating a wiring short, connector corrosion, or solenoid failure.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Solenoid Control Voltage 9–14V during activation Below 4.5V or open circuit detected
Circuit Resistance 4–8 ohms coil resistance Above 15 ohms or infinite (open)
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
VVT solenoid connector
Inspect and clean the connector pins on Bank 2's exhaust camshaft solenoid; corrosion often causes low voltage signals.
2
Engine wiring harness (Bank 2 exhaust circuit)
Check for pinched, cracked, or corroded wires between the ECM and the VVT solenoid; repair or replace damaged sections.
3
VVT solenoid (Bank 2 exhaust)
If connector and wiring are clean, replace the solenoid itself, as internal coil failure prevents adequate voltage response.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code P0079 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.
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How to Clear Code P0079

What happens after you fix the fault

Once the fault is repaired, P0079 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When
  • Fault has been diagnosed and repaired
  • You want to confirm the repair worked
  • Code appeared after a sensor was cleaned
⚠️ Do Not Clear When
  • Preparing for an emissions/PUC test
  • Root cause is still undiagnosed
  • Check engine light is flashing
Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.