What Does P1391 Mean?
The engine control module has detected that the variable valve timing system on Bank 2 (the side opposite cylinder #1) is advancing the camshaft timing beyond the commanded position. This indicates the cam phaser is unable to properly control or hold the camshaft position.
Common Causes
35%
Failed or sticking VVT/cam phaser solenoid on Bank 2
25%
Low engine oil level or incorrect oil viscosity affecting VVT system operation
20%
Worn or damaged cam phaser mechanism on Bank 2
15%
Clogged VVT oil control valve or restricted oil passages
5%
Faulty camshaft position sensor providing incorrect timing data
Diagnostic Steps
1
Step 1: Check engine oil level and condition; verify correct oil viscosity is being used
2
Step 2: Monitor VVT solenoid command vs actual cam timing using live data while engine is running
3
Step 3: Test VVT solenoid operation and resistance on Bank 2; check for sticking or debris
4
Step 4: Inspect cam phaser for mechanical wear or locking mechanism failure
5
Step 5: Verify camshaft position sensor signal quality and compare Bank 1 vs Bank 2 operation
Estimated Repair Cost
$200 - $1,200
Parts + labor, varies by vehicle and location
The engine control module has detected that the variable valve timing system on Bank 2 (the side opposite cylinder #1) is advancing the camshaft timing beyond the commanded position. This indicates the cam phaser is unable to properly control or hold the camshaft position.
The most common cause of P1391 (Variable Cam Timing Overadvanced (Bank #2)) is: Failed or sticking VVT/cam phaser solenoid on Bank 2
Typical repair costs for P1391 range from $200 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may experience reduced power, rough idle, and poor fuel economy but is generally safe to drive short distances. Continued operation may cause internal engine damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1391 to identify the root cause.
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Quick Info
Category
Powertrain
System
Variable Valve Timing System
Difficulty
Type
Manufacturer
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