P2646 OBD-II Trouble Code: 'A' Rocker Arm Actuator System Performance / Stuck Off Bank 1

P2646 code definition

'A' Rocker Arm Actuator System Performance or Stuck Off Bank 1

What the P2646 code means

P2646 is an OBD-II generic code for the engine control module (ECM) detecting the 'A' rocker arm actuator control circuit for bank 1 has a performance problem or is stuck in the off position.

What causes the P2646 code?

• The ECM detects a problem in the rocker arm system for bank 1.
• The oil passages are clogged or the oil pressure is not up to specifications.
• The rocker arm actuator is clogged with sludge or is sticking intermittently.
• The engine may have excessive sludge binding the rockers from moving or the oil is too thick.
• The incorrect oil viscosity is being used. Too thick of an oil will cause the system to not work as designed.

What are the symptoms of the P2646 code?

• The engine valve train will not move as designed causing a low power condition.
• The Check Engine Light will be illuminated.
• The valve train may be excessively noisy if one or more rockers are stuck in the incorrect position.

How does a mechanic diagnose the P2646 code?

• Scans codes and documents the code in the ECM and views the freeze frame data for the code
• Verifies the oil is full of the correct viscosity oil
• Performs the manufacturer pinpoint test on the 'A' rocker arm actuator system since testing may be different between applications and manufacturers

Common mistakes when diagnosing the P2646 code?

• Replacing the actuator without verifying the actuator is the cause of the problem
• Failing to clear the ECM codes after the system is repaired
• Failing to identify that incorrect oil viscosity is being used causing the code

How serious is the P2646 code?

Code P2646 is a code for the 'A' rocker arm control circuit performance problem. When the system is not working correctly, the rocker arms are not moving to the different position causing a low power situation.

What repairs can fix the P2646 code?

• Replacing the 'A' rocker arm actuator
• Repairing the wiring harness or connector to the actuator
• Changing the oil and filter to the correct viscosity oil
• Flush the engine passages of sludge from lack of oil changes

Additional comments for consideration regarding the P2646 code

Code P2646 is not a very common code since most vehicles do not have actuators for the rocker arms of the engines they manufacture. The vehicles that have variable rockers that use this code are known to get this code when the engine gets sludged up from lack of oil changes at the proper interval, or if the oil is too thick of a viscosity and does not flow properly through the small passages as required. Normal oil change intervals with the correct oil viscosity will usually fix most of these codes if the engine is not too sludged up.

Need help with a P2646 code?

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