Advanced Diagnostics

Advanced Diagnostics - DTC P2648:Rocker Arm Oil Control Solenoid Circuit Low Voltage (Engine Type: K20Z3)






General Description
The VTEC system activates the rocker arm oil control solenoid by command from the engine control module (ECM), and it charges/discharges the hydraulic circuit of the VTEC mechanism that switches valve timing between low and high. If the return signal is OFF (low) when the ECM outputs the ON (high) signal to the rocker arm oil control solenoid, the ECM detects a malfunction and stores a DTC.

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 outputs the ON (high) signal to the rocker arm oil control solenoid.

Confirmation Procedure with the HDS
Do the VTEC TEST in the INSPECTION MENU with the HDS.

Driving Pattern
1. Start the engine. Hold the engine speed at 3,000 rpm without load (in neutral) until the radiator fan comes on.
2. Drive the vehicle in a lower gear at 4,000 rpm or more with a manifold absolute pressure (MAP) value of 12 kPa (3.5 inHg, 90 mmHg) 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 setting the DTC
When a malfunction is detected, the MIL comes on and a Pending DTC, a Confirmed DTC, and the freeze data are stored in the ECM memory.

Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.