P0079 explained: Bank 1 exhaust-side variable valve actuator is not responding the way the PCM commands. Common on Honda VTEC, GM AFM, and Nissan VVEL engines. A clogged oil passage or low oil pressure mimics a bad solenoid - check oil first.
🎯 Top Causes & Probability
50%
#1 - Most Likely
Failed Exhaust VVT/Lift Solenoid (Bank 1)
The solenoid coil has shorted internally or the spool valve is stuck. Most common after 80k miles, especially with skipped oil changes.
🔨 Part
$45-$220
👨🔧 Labor
$80-$200
⚡ DIY
Medium
30%
#2 - Check First
Sludged / Clogged Oil Control Passage
Dirty oil clogs the small oil passage that operates the solenoid. The solenoid is fine but cannot move. An oil change with engine flush often clears this.
🔨 Part
$25-$80
👨🔧 Labor
$0-$150
⚡ DIY
Easy
15%
#3 - Less Common
Wiring or Connector Damage
Heat near the cylinder head melts the connector or chafes the harness. Inspect the pigtail for melted insulation or green corrosion.
🔨 Part
$15-$60
👨🔧 Labor
$60-$180
⚡ DIY
Medium
🚗 Most Affected Vehicles
🔧 Step-by-Step Diagnosis
- Check engine oil level and condition. Low or sludgy oil mimics solenoid failure. Top off or change oil first if it is dirty.
- Locate the bank 1 exhaust solenoid (driver side on most V engines, single bank on inline engines) and inspect the harness for melted insulation or oil contamination.
- Unplug the connector and measure solenoid resistance. Most read 7-15 ohms. Open circuit or shorted readings confirm the solenoid is dead.
- Back-probe the connector with the key on, engine off. You should see battery voltage on one pin. No voltage points to a wiring or PCM driver fault.
- Clear the code, road test for 10 minutes, and recheck. If P0079 returns immediately under load, replace the solenoid.
❓ Frequently Asked Questions
Can I drive with a P0079 code?
Yes, short-term. The engine drops out of variable valve mode and runs on a default cam profile. You will lose 1-3 MPG and some top-end power. Driving for weeks can stress the timing chain - fix it within a month.
Will an oil change fix P0079?
Sometimes. If the solenoid screen is clogged with sludge, a fresh oil change with the correct viscosity often clears the code. Try it before buying a $200 solenoid.
How much does P0079 repair cost?
Typically $130-$420 total. The solenoid itself runs $45-$220, plus 1-2 hours of labor. DIY is possible on most engines with basic tools.
Will P0079 fail emissions?
In most US states, yes. Any active powertrain code triggers a fail on OBD-II readiness inspection regardless of tailpipe numbers.
What is the difference between P0079 and P0078?
P0078 is a generic exhaust solenoid circuit fault. P0079 is specifically a low-voltage condition (short to ground or open circuit on the control side).