Advanced Diagnostics

DTC P2648: Rocker Arm Oil Control Solenoid Circuit Low Voltage




General Description
The VTEC system switches the valve timing by Opening and closing the oil passage to the high/low camshaft switching mechanism. The rocker arm oil control solenoid, controlled by the engine control module (ECM)/powertrain control module (PCM), Opens and closes the oil passage, which controls VTEC operation.

The intelligent pre-driver drives the rocker arm oil control solenoid by receiving the drive direction output at the CPU in the ECM/PCM. When the rocker arm oil control solenoid output is OFF (low) and this condition continues for a certain time or more in response to the rocker arm oil control solenoid ON (high) drive instruction to the intelligent pre-driver, a malfunction is detected and a DTC is stored.




Monitor Execution, Sequence, Duration, DTC Type, OBD Status




Enable Conditions

Malfunction Threshold
The return signal is OFF (low) for at least 1.1 seconds when the ECM/PCM outputs the ON (high) signal to the rocker arm oil control solenoid (VTEC solenoid valve).

Driving Pattern
1. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on.
2. Drive the vehicle in a lower gear at 4,750 rpm or more for at least 7 seconds.

- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details

Conditions for illuminating the MIL
When a malfunction is detected, the MIL comes on and the DTC and the freeze frame data are stored in the ECM/PCM memory.

Conditions for clearing the MIL
The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the diagnostic runs.

The MIL, the DTC, and the freeze frame data can be cleared by using the scan tool Clear command or by disconnecting the battery.