P0079
UniversalExhaust Valve Control Circuit Low (Bank 2)
Medium SeverityThis code indicates that the engine's computer has detected a voltage level lower than expected in the circuit that controls the exhaust valve actuator on engine Bank 2. This typically prevents the variable valve timing system from effectively adjusting the exhaust valves, leading to potential issues like reduced engine performance and fuel efficiency.
⚠️ Before You Begin (Safety First)
Always disconnect the battery before performing any electrical work. Ensure the engine is cool to the touch before working on engine components to prevent burns. Use appropriate personal protective equipment, including safety glasses and gloves, to protect against chemicals and hot surfaces.
Common Symptoms
- Check Engine Light (MIL) illuminated
- Rough idle or unstable engine idle
- Reduced engine performance or power
- Decreased fuel economy
- Engine hesitation or stumbling during acceleration
Common Causes
- Faulty exhaust valve control solenoid (VVT actuator) on Bank 2
- Wiring harness issues such as chafed, broken, or corroded wires leading to the solenoid
- Poor electrical connection at the solenoid connector or Engine Control Module (ECM) connector
- Insufficient engine oil pressure or incorrect engine oil viscosity affecting VVT operation
- Faulty Engine Control Module (ECM) (less common)
Frequently reported on: Ford F-150 (2004-2010), Toyota Camry (V6, 2007-2011), Honda Pilot (V6, 2005-2008), Nissan Altima (V6, 2007-2012), Chevrolet Silverado (V8, 2007-2013)
Diagnostic Steps
- Visually inspect the wiring harness and electrical connector for the exhaust valve control solenoid on Bank 2 for any signs of damage, corrosion, or loose connections. Repair or replace as necessary.
- Verify the engine oil level is correct and that the oil is clean and of the manufacturer-recommended viscosity, as low oil pressure or dirty oil can impair VVT functionality.
- Using a multimeter, test the resistance of the exhaust valve control solenoid and compare it to the vehicle manufacturer's specifications. A reading outside the specified range indicates a faulty solenoid.
- If accessible, carefully remove and clean the exhaust valve control solenoid. Sometimes, sludge or debris can cause it to stick or malfunction. Reinstall with a new gasket if required.
- If testing confirms the solenoid is faulty or wiring damage is irreparable, replace the exhaust valve control solenoid (VVT actuator) on Bank 2.
👨🔧 When to Call a Professional
If you have thoroughly inspected the wiring and connectors and even replaced the exhaust valve control solenoid, but the P0079 code persists, it's time to consult a certified mechanic. Further diagnosis may require specialized tools like an oscilloscope to test the ECM's output signals or to rule out an internal ECM fault, which is a rare but possible cause.
Commonly Asked Questions
What does 'Bank 2' mean for a P0079 code?
Bank 2 refers to the side of the engine that does not contain cylinder number one. On V-type engines, this is typically the driver's side bank. It's important to identify the correct bank for diagnosis and repair.
Can I drive my vehicle with a P0079 code?
While your vehicle may still be drivable, it is not recommended to drive for extended periods with a P0079 code. It can lead to reduced engine performance, decreased fuel economy, and potentially further engine damage if the underlying issue is not addressed.
How do I locate the exhaust valve control solenoid on Bank 2?
The exhaust valve control solenoid (also known as a VVT actuator or oil control valve) is typically located on the cylinder head of Bank 2, usually near the exhaust camshaft. Consult your vehicle's specific service manual for its exact location.
Is low engine oil or dirty oil related to the P0079 code?
Yes, variable valve timing systems often rely on engine oil pressure to operate the actuators. Low oil level, dirty oil, or using an incorrect oil viscosity can prevent the solenoid from functioning correctly, potentially triggering this code.
Do I need special tools to diagnose and fix a P0079 code?
A multimeter is highly recommended for accurately testing the electrical circuit and solenoid resistance. A basic OBD-II scan tool is needed to read and clear the code. While not always strictly necessary, a more advanced scan tool with live data capabilities can help monitor sensor readings and actuator commands, aiding in diagnosis.