P0079
Fix within a few daysExhaust Valve Control Solenoid Circuit Low (Bank 1)
Code P0079 means your exhaust valve timing solenoid circuit on Bank 1 has a low voltage signal. Common causes: Faulty VVT solenoid (70%), wiring issues (20%). Drivability: Yes, but fix soon. Repair cost: $50-$200 DIY, $150-$500 professional.
Can I Drive With P0079?
Yes, for short trips only
Essential trips under 10 miles, avoid highways and heavy acceleration
Stop driving immediately if: Flashing CEL, loud engine noises, significant power loss, or engine stalling frequently.
Symptoms of P0079
- 1Rough or unstable engine idle
- 2Reduced engine power or acceleration
- 3Decreased fuel economy
- 4Engine may run louder than usual
- 5Engine may stall at low speeds
Common Causes of P0079
Parts most likely causing this code, ranked by probability
The variable valve timing (VVT) solenoid for the exhaust valves on Bank 1 has an internal electrical fault, causing a low voltage signal.
70% of P0079 cases are fixed by replacing this part
Damaged, corroded, or loose wiring or a faulty connector to the exhaust VVT solenoid on Bank 1 can cause a low circuit signal.
20% of P0079 cases are fixed by repairing wiring or connectors
A rare internal fault within the PCM's driver circuit for the exhaust VVT solenoid can send an incorrect low voltage signal.
10% of P0079 cases are fixed by replacing the PCM
Check These First (Before Buying Parts)
- Check engine oil level and condition: Ensure oil is full and clean. Low or dirty oil can affect VVT operation.
- Inspect the wiring harness and connector to the exhaust VVT solenoid (Bank 1) for any visible damage, fraying, corrosion, or loose connections.
How to Diagnose P0079
- 1Check engine oil level and condition; ensure it's full and clean.
- 2Visually inspect the exhaust VVT solenoid (Bank 1) wiring harness and connector for damage, corrosion, or loose connections.
- 3Disconnect the solenoid and check for continuity and resistance across the solenoid terminals using a multimeter; compare to factory specifications.
- 4Check for proper voltage supply and ground at the solenoid connector using a multimeter.
- 5If the solenoid and wiring test good, a professional diagnosis of the PCM may be necessary.
P0079 on Popular Vehicles
Toyota Camry
2007-2024Toyota's VVT-i solenoids are common failure points. Ensure you use genuine Toyota or high-quality aftermarket parts for best results. Dirty engine oil can accelerate solenoid wear.
75% fixed by replacing the VVT-i solenoid
Honda Accord
2003-2024Honda's VTEC system can also trigger P0079. Check for oil leaks around the solenoid housing and ensure the oil pressure switch is functioning correctly, as it's often integrated or nearby.
70% fixed by replacing the VVT solenoid
Ford F-150
2004-2024Ford's VCT (Variable Cam Timing) solenoids are known to fail, especially on higher mileage engines. These are often located under the valve covers or easily accessible on the front of the cylinder head. Ensure proper engine oil viscosity.
80% fixed by replacing the VCT solenoid
Frequently Asked Questions
What does P0079 mean?
P0079 indicates that the Powertrain Control Module (PCM) has detected a low voltage condition in the electrical circuit for the exhaust variable valve timing (VVT) solenoid on engine Bank 1.
Can I drive with P0079?
Yes, you can drive with P0079, but you will experience reduced engine performance, lower fuel economy, and potentially a rough idle. Fix this within a few days to prevent further issues.
Will P0079 clear itself?
No, P0079 will not clear itself. The underlying electrical or mechanical issue causing the low circuit signal must be repaired before the code will clear. You will need to clear it with a scan tool after the repair.
How do I fix P0079 myself?
Start by checking your engine oil level and condition. Then, inspect the wiring and connector to the exhaust VVT solenoid on Bank 1 for any damage. If those look good, replace the exhaust VVT solenoid itself. This is the most common fix.
How much does it cost to fix P0079?
A DIY fix for P0079 typically costs $50-$200 for a new exhaust VVT solenoid. If you take it to a shop, expect to pay $150-$500, which includes parts and labor.
P0079 keeps coming back - why?
If P0079 keeps returning, it's likely because the initial diagnosis missed the true cause. This could be due to a persistent wiring issue, a faulty PCM, or a new solenoid that was defective. Ensure your engine oil is clean and at the correct level, as dirty oil can sometimes affect VVT operation.
Will P0079 fail emissions/smog test?
Yes, P0079 will cause your vehicle to fail an emissions or smog test. The check engine light being on is an automatic failure in most jurisdictions, and issues with valve timing directly impact emissions.
What's the difference between P0079 and P0078?
P0079 indicates a 'Circuit Low' condition for the exhaust VVT solenoid on Bank 1, meaning the PCM is seeing too little voltage. P0078 typically indicates a 'Circuit Range/Performance' or 'Circuit High' issue for the same solenoid, meaning the signal is out of expected range or too high.
P0079 on Toyota Camry?
On a Toyota Camry, P0079 often points to a failing exhaust VVT-i solenoid. These solenoids can get clogged with sludge or fail electrically over time. Replacing the solenoid and ensuring clean engine oil is usually the fix.
Questions to Ask Your Mechanic
Did you test the resistance of the exhaust VVT solenoid on Bank 1 and compare it to factory specifications?
Good answer: Yes, I measured the resistance at [X ohms] and it was outside the specified range of [Y-Z ohms], indicating an internal fault with the solenoid.
What voltage and ground readings did you get at the solenoid connector?
Good answer: I confirmed battery voltage (around 12V) at the power wire and a solid ground. The issue is not with the power supply to the solenoid.
Repair Cost Estimate
DIY Repair
Parts only
$50-$200
Shop Repair
Parts + labor
$150-$500
Save $100-$300 by doing it yourself
Difficulty
intermediate
Time
1-2 hours
Intermediate - requires basic hand tools, a multimeter for testing, and some familiarity with engine components. Access to the solenoid can vary by vehicle.
Cost of Waiting
Ignoring P0079 can lead to continued poor fuel economy, reduced engine power, and potentially increased wear on other engine components due to incorrect valve timing. A $100 solenoid replacement now prevents potential long-term engine damage.
While You're In There...
VVT systems are highly dependent on clean engine oil. If your oil is dirty or overdue for a change, replacing it ensures proper solenoid function and prevents future issues.
Many VVT solenoids use O-rings or gaskets to seal against oil leaks. Replacing these ensures a leak-free repair and is minimal extra cost while the solenoid is out.
Tools You'll Need
- OBD-II scan tool
- Multimeter
- Socket set
- Wrench set
- Screwdriver set
- Engine oil (if low or dirty)
P0079 is a common VVT system code. Most repairs involve replacing a single solenoid, which is a straightforward job for an intermediate DIYer, and your engine will run smoothly afterward.
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Your Next Steps
Step 1: Check your engine oil level and condition. Top off or change the oil if necessary, as VVT systems rely on clean, proper oil pressure.
Step 2: Visually inspect the wiring and connector for the exhaust VVT solenoid on Bank 1. Look for any signs of damage, corrosion, or looseness. Repair as needed.
Step 3: If the wiring is good, test the exhaust VVT solenoid (Bank 1) with a multimeter for proper resistance. If it's out of spec, replace the solenoid. Parts you'll likely need: 1 exhaust VVT solenoid.