DTC Troubleshooting

DTC Troubleshooting: P2648

DTC P2648: Rocker Arm Oil Control Solenoid Circuit Low Voltage

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information. Initial Inspection and Diagnostic Overview

1. Turn the ignition switch to ON (II).

2. Clear the DTC with the HDS.

3. Do the VTEC TEST in the INSPECTION MENU with the HDS.

Is the result OK?
YES - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the rocker arm oil control solenoid and the ECM.

NO - Go to step 4.


4. Turn the ignition switch to LOCK (0).

5. Disconnect the rocker arm oil control solenoid 2P connector.

6. At the solenoid side, measure the resistance between rocker arm oil control solenoid 2P connector terminals No. 1 and No. 2.

Is there 14-30 Ohms at room temperature?
YES - Go to step 7.

NO - Go to step 10.






7. Jump the SCS line with the HDS.

8. Disconnect ECM connector B (44P).

9. Check for continuity between ECM connector terminal B34 and body ground.

Is there continuity?
YES - Repair short in the wire between the ECM (B34) and the rocker arm oil control solenoid, then go to step 11.

NO - Go to step 18.






10. Replace the rocker arm oil control valve. Service and Repair

11. Reconnect all connectors.

12. Turn the ignition switch to ON (II).

13. Reset the ECM with the HDS.

14. Do the ECM idle learn procedure. ECM Idle Learn Procedure

15. Do the VTEC TEST in the INSPECTION MENU with the HDS.

16. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P2648 indicated?
YES - Check for poor connections or loose terminals at the rocker arm oil control solenoid and the ECM, then go to step 1.

NO - Go to step 17.


17. Monitor the OBD STATUS for DTC P2648 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?
YES - Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 16, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the rocker arm oil control solenoid and the ECM, then go to step 1. If the screen indicates NOT COMPLETED, go to step 15.


18. Reconnect all connectors.

19. Update the ECM if it does not have the latest software, ECM Update or substitute a known-good ECM. Initial Inspection and Diagnostic Overview

20. Do the VTEC TEST in the INSPECTION MENU with the HDS.

21. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P2648 indicated?
YES - Check for poor connections or loose terminals at the rocker arm oil control solenoid and the ECM. If the ECM was updated, substitute a known-good ECM, Initial Inspection and Diagnostic Overview then go to step 20. If the ECM was substituted, go to step 1.

NO - Go to step 22.


22. Monitor the OBD STATUS for DTC P2648 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?
YES - If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM. Service and Repair If any other Temporary DTCs or DTCs were indicated in step 21, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the rocker arm oil control solenoid and the ECM. If the ECM was updated, substitute a known-good ECM, Initial Inspection and Diagnostic Overview then go to step 20. If the ECM was substituted, go to step 1. If the screen indicates NOT COMPLETED, go to step 20.