DTC Troubleshooting: P2646 (22)
DTC P2646:
 Rocker Arm Oil Pressure Switch Circuit Low Voltage
Special Tools Required
NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.
  1. Check the engine oil level.
Is the level OK?
YES -
Go to Step 2 .
NO -
Adjust the engine oil to the proper level, then go to Step 20 .
  1. Turn the ignition switch ON (II).
  1. Clear the DTC with the HDS.
  1. 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 pressure switch, the rocker arm oil control solenoid, and the ECM.■
NO -
Go to Step 5 .
  1. Turn the ignition switch OFF.
  1. Disconnect the rocker arm oil pressure switch 2P connector.
  1. Turn the ignition switch ON (II).
  1. Check the VTEC PRES SW in the DATA LIST with the HDS.
Is SWITCH ON indicated?
YES -
Go to Step 16 .
NO -
Go to Step 9 .
  1. Turn the ignition switch OFF.
  1. Remove the rocker arm oil pressure switch (A), and install the special tools as shown, then install the rocker arm oil pressure switch in the oil pressure gauge attachment (B).
    NOTE: Install the parts in the reverse order of removal with a new O-ring.
  1. Reconnect the rocker arm oil pressure switch 2P connector.
  1. Start the engine.
  1. Do the VTEC TEST in the INSPECTION MENU with the HDS.
  1. Check the oil pressure.
Does the oil pressure increase to at least 392 kPa(4.0 kgf/cm 2 , 56.9 psi)?
YES -
NO -
Inspect the VTEC system. If it is OK. replace the rocker arm oil control valve, then go to Step 19 .
  1. Turn the ignition switch OFF.
  1. Disconnect ECM connector C (44P).
  1. Check for continuity between ECM connector terminal C22 and body ground.
Is there continuity?
YES -
Repair short in the wire between the ECM (C22) and the rocker arm oil pressure switch, then go to Step 19 .
NO -
Go to Step 26 .
  1. Reconnect all connectors.
  1. Turn the ignition switch ON (II).
  1. Reset the ECM with the HDS.
  1. Do the VTEC TEST in the INSPECTION MENU with the HDS.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P2646 indicated?
YES -
Check for poor connections or loose terminals at the rocker arm oil pressure switch, the rocker arm oil control solenoid and the ECM, then go Step 1 .
NO -
Go to Step 25 .
  1. Monitor the OBD STATUS for DTC P2646 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 24 , go to the indicated DTC's troubleshooting.■
NO -
If the screen indicates FAILED, go to Step 1 and recheck. If the screen indicates NOT COMPLETED, go to Step 23 and recheck.
  1. Reconnect all connectors.
  1. Do the VTEC TEST in the INSPECTION MENU with the HDS.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P2646 indicated?
YES -
Check for poor connections or loose terminals at the rocker arm oil pressure switch, the rocker arm oil control solenoid, and the ECM. If the ECM was updated, substitute a known-good ECM, then go to Step 28 . If the ECM was substituted, go to Step 1 .
NO -
Go to Step 30 .
  1. Monitor the OBD STATUS for DTC P2646 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. If any other Temporary DTCs or DTCs were indicated in Step 29 , 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 pressure switch, the rocker arm oil control solenoid, and the ECM. If the ECM was updated, substitute a known-good ECM, then go to Step 28 . If the ECM was substituted, go to Step 1 . If the screen indicates NOT COMPLETED, go to Step 28 and recheck.