The OBD2 code P0029 indicates that the Engine Control Module (ECM) has detected a performance or range issue with the Exhaust Valve Control Solenoid circuit on Bank 2. This system is part of your vehicle's Variable Valve Timing (VVT), which optimizes engine efficiency and power. When the solenoid cannot move the valve to the commanded position—often due to oil quality issues or electrical failure—the P0029 code is triggered. While the car may still be drivable, ignoring this code can lead to poor fuel economy and potential engine damage over time.
Common Symptoms
- Check Engine Light (CEL) illuminated
- Reduced engine performance and power
- Noticeable decrease in fuel efficiency
- Rough engine idling
- Hesitation during acceleration
Potential Causes
- Low engine oil level
- Dirty or contaminated engine oil (sludge)
- Faulty Exhaust Valve Control Solenoid (Bank 2)
- Open or shorted wiring harness
- Loose or corroded electrical connectors
Tools Required
- OBD2 Scanner
- Digital Multimeter
- Socket Set (8mm, 10mm, 12mm)
- Ratchet and Extensions
- Fresh Engine Oil and Filter
- Electrical Contact Cleaner
Diagnostic Steps
Step 1: Initial Scan and Oil Level Inspection
Start by connecting your OBD2 scanner to the vehicle's port to confirm P0029 and check for any related codes (like oil pressure codes). Since the VVT system relies heavily on hydraulic oil pressure, pull the engine oil dipstick. Ensure the oil level is at the 'Full' mark and inspect the color. If the oil is pitch black, gritty, or milky, the hydraulic passages in the solenoid may be clogged with sludge, which is the most common cause of this code.
Step 2: Visual Inspection of the Wiring and Connector
Locate the exhaust valve control solenoid on Bank 2 (the side of the engine that does not contain cylinder #1). Inspect the electrical connector for signs of corrosion, oil soaking, or loose pins. Trace the wiring harness back as far as possible to check for frayed wires or heat damage from exhaust components. Use electrical contact cleaner if you find any oil or dirt inside the plug.
Step 3: Test the Solenoid Resistance
Set your digital multimeter to the Ohms (resistance) setting. Disconnect the electrical connector from the Bank 2 exhaust valve control solenoid. Place the multimeter probes on the two terminals of the solenoid. Compare your reading to the manufacturer's specifications (typically between 7 and 12 ohms). An 'OL' (Open Loop) reading or a reading near 0 ohms indicates an internal short or break, meaning the solenoid must be replaced.
Step 4: Bench Test the Solenoid Operation
Remove the solenoid from the engine using a socket wrench. Be careful not to drop any mounting bolts into the engine bay. Once removed, apply 12 volts of power and a ground from the car battery to the solenoid terminals using jumper wires. You should hear a distinct 'click' and see the internal pintle move. If the solenoid is sluggish or does not move at all, it is likely seized by sludge or mechanical failure.
Step 5: Replace the Solenoid and Change the Oil
If the solenoid failed the resistance or bench test, install a new high-quality replacement. Even if the solenoid seems functional, if your oil was dirty, perform a full oil and filter change. Clean oil is critical for the VVT system to function. Lubricate the O-ring on the new solenoid with fresh oil before sliding it into the cylinder head and tightening the mounting bolt to the manufacturer's torque spec.
Step 6: Clear the Code and Road Test
Reconnect the electrical harness. Use your OBD2 scanner to clear the P0029 code from the ECM's memory. Start the engine and let it reach operating temperature. Take the vehicle for a 15-20 minute road test, ensuring you vary your speeds to allow the VVT system to engage. After the test, scan the system again to ensure the 'Permanent' or 'Pending' status of the code has disappeared.
💡 Mechanic's Pro Tips
- Always use the oil viscosity recommended by the manufacturer; using thicker oil can prevent the VVT solenoid from operating correctly.
- Bank 2 is the side of the engine that does not house the number one cylinder. On transverse V6 engines, this is usually the bank closest to the radiator.
- Before replacing the solenoid, check for a small filter screen behind or inside the solenoid housing; these screens often clog and cause P0029.
Frequently Asked Questions
Q: Is it safe to drive with a P0029 code?Checked?" "answer":"You can drive the vehicle, but it will suffer from reduced performance and poor fuel economy. Prolonged driving with VVT issues can occasionally lead to timing chain wear or engine sludge buildup.
Q: How much does it cost to fix P0029?" "answer":"If you do it yourself, a new solenoid typically costs between $50 and $150. If you take it to a shop, parts and labor usually range from $200 to $400 depending on your vehicle's make and model.
Q: Can a low oil level cause P0029?" "answer":"Yes, the VVT system uses oil pressure to move the valves. If the oil level is too low, there isn't enough hydraulic pressure to move the solenoid, triggering the range/performance code.
Conclusion
Fixing a P0029 code is a manageable task for most DIYers, often boiling down to oil maintenance or a simple solenoid swap. By ensuring your engine oil is clean and the exhaust valve control solenoid is functioning correctly, you restore your engine's efficiency and avoid more costly repairs down the road. Always prioritize safety by working on a cool engine and using the correct tools for the job.