P2646 CODE – WHAT DOES IT MEAN & HOW TO FIX IT

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.

Meaning

Some vehicles have a VTEC (Variable Valve Timing & Lift Electronic Control) system; for increasing fuel efficiency and performance. This VTEC is responsible for controlling the rocker arm control system through the powertrain control module (PCM). The Rocker Arm Control Solenoid supplies hydraulic pressure to the Variable Timing mechanism. The rocker arm oil pressure switch monitors and verifies the oil pressure, so the timing mechanism works properly. If PCM is not receiving back the required voltage single from the rocker arm oil pressure switch, it may trigger code P2646. 

Causes

Although the P2646 code error is linked with oil problems/oil sludge, there could be many other reasons.

Listed below are some possible causes for the P2646 code to appear.

• A non-standard viscous oil is being used
• A low level of oil or contaminated engine oil is used
  • A low level or thin oil will not generate enough pressure to operate the VTEC system. This problem can occur if the last oil change was done improperly or if the oil is diluted by the fuel in the crankcase (injections or leakage, probably cold idling).
• Electrical problems, outdated PCM software, poor wiring/connection, VTEC oil pressure sensor failure or faulty rocker arm (VTEC) oil control solenoid.
  • Check for rust, missing or bent pins, and that electrical connectors are completely connected. Examine wire harnesses for visible harm.
• The engine control module (ECM) identifies an issue in the rocker arm system for bank-1
• Blockage in rocker arm actuator.
• The oil pressure is not up to the mark or clogging in oil passages
• The engine may have extreme sludge binding the rockers from moving (engine oil sludge is caused by infrequent oil changes) VTEC will not work if oil passages are blocked. An engine oil flush can help clean out deposits and restore work, as can switching to a synthetic blend or full-synthetic oil.

Symptoms

Although causes of the P2646 code may vary by car make and model, the symptoms are or may be similar. 

• The Check Engine Light will be illuminated
• Decreased engine performance because the engine valve is not moving as it should
• There will be extreme noise if one or more rockers are stuck in the wrong position
• Increased fuel consumption

Diagnosis

It is essential to diagnose this code error thoroughly and professionally. Misdiagnoses can further harm the vehicle. Some steps for diagnosis related to this code are:

• Verify that the engine oil is maintaining the required level and has the correct oil viscosity
• Inspect all electrical connection and sensors and their integrity
• Check all wired connection
• Inspect the ‘A’ rocker arm actuator system
• Check the oil passages if they are clear      or clogged.
• Mount the on-board diagnostic-II (OBD-II) scanner and record all solved/put away codes and freeze outline information. Having freeze outline information is significant as it can advise in what condition the vehicle was in when the P2646 code was displayed. 

Common mistakes

The common mistakes which may occur while addressing ODC P2646 are:

• Failure to identify the correct viscosity of the oil
• Replace the rocker arm actuator without finding out the real cause of the problem
• The engine control module (ECM) codes history is not removed from ECM software after repairing the vehicle

How serious is this?

This error code could cause a serious problem to the engine of the vehicle. Due to poor engine performance, fuel consumption may also increase.

What repairs can fix the code?

There is no single method to fix the P2646 code since there are a few potential causes that can trigger it. Following are the possible solutions to mitigate this error: 

• Repair and replace the wiring apparatus or connector to the actuator
• Use the required oil, clean air and oil filter for suitable viscosity;
• Flush the engine passages There shouldn’t be any sludge in the engine      oil passage. 
• Install a new “A” rocker arm actuator

Additional Information About the Code P2646

The P2646 is not a standard error code and does not appear in all vehicles. Instead, those automobiles that have a rocker arm actuator face this issue. Most      cars, like the Honda      A     ccord have such issues, because of the presence of a rocker arm actuator.     

Related codes

Other related error codes related to code P2646 are:

• P2645 “A” Rocker Arm Actuator Control Circuit/Open (Bank 1)

• P2647 “A” Rocker Arm Actuator System Stuck on (Bank 1)

• P2648 “A” Rocker Arm Actuator Control Circuit Low (Bank 1)

• P2649 “A” Rocker Arm Actuator Control Circuit High (Bank 1)

• P2650 “B” Rocker Arm Actuator Control Circuit/Open (Bank 1)

• P2651 “B” Rocker Arm Actuator System Performance or Stuck Off (Bank 1)

• P2652 “B” Rocker Arm Actuator System Stuck on (Bank 1)

• P2653 “B” Rocker Arm Actuator Control Circuit Low (Bank 1)

• P2654 “B” Rocker Arm Actuator Control Circuit High (Bank 1)

• P2655 “A” Rocker Arm Actuator Control Circuit/Open (Bank 2)

• P2656 “A” Rocker Arm Actuator System Performance or Stuck Off (Bank 2)

• P2657 “A” Rocker Arm Actuator System Stuck on (Bank 2)

• P2658 “A” Rocker Arm Actuator Control Circuit Low (Bank 2)

• P2659 “A” Rocker Arm Actuator Control Circuit High (Bank 2)

• P2660 “B” Rocker Arm Actuator Control Circuit/Open (Bank 2)

• P2661 “B” Rocker Arm Actuator System Performance or Stuck Off (Bank 2)

• P2662 “B” Rocker Arm Actuator System Stuck on (Bank 2)

• P2663 “B” Rocker Arm Actuator Control Circuit Low (Bank 2)

• P2664 “B” Rocker Arm Actuator Control Circuit High (Bank 2)

Conclusion

This diagnostic trouble code does not represent any genuine threat to the driver. However, P2646 is responsible for the low power situation, and this error code should be fixed at the earliest possibility. In addition, one should consult with a mechanic to inspect your vehicle as early as possible to avoid any damage.