P3491
Cylinder Deactivation System Performance Bank 2
The engine control module has detected that the cylinder deactivation system on bank 2 is not performing as expected. Closed-loop monitoring of pressure response, valve timing or misfire counters during transitions indicates the system fails to deactivate or reactivate cylinders within calibrated limits.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: shop_only
Common causes
Ordered by how often each turns out to be the cause.
- Switching lifter stuck or wornCommon
- Insufficient oil pressurePossible
- Solenoid slow or contaminatedPossible
Parts involved
- Cylinder Deactivation Solenoid
- Lifter
- Oil Control Valve
P3491 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.