Advanced Diagnostics

Advanced Diagnostics - DTC P128C: Rocker Arm Oil Pressure Sensor A Stuck Low











General Description
Two rocker arm oil control solenoids open and close according to commands from the powertrain control module (PCM), and oil pressure is applied to and then released from the valve pause system (VPS) to change operation of the valve. The PCM monitors the oil pressure of the switching mechanism using rocker arm oil pressure sensors on the rocker arm oil control solenoid. The PCM compares the oil pressure based on the PCM command and the oil pressure condition of the rocker arm oil pressure sensor to determine if the system is operating normally.

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






Enable Conditions






Malfunction Threshold
The following conditions occur for at least 2.0 seconds in the normal valve lift mode 2.






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 P or N) until the radiator fan comes on.
2. Drive at a steady speed of 12 mph (18 km/h) or more and engine speed between 900 - 3,000 rpm for at least 2 seconds, or drive at steady speed of 12 mph (18 km/h) or more and engine speed between 1,000 - 3,000 rpm, and decelerate with the throttle valve fully closed for at least 2 seconds.
3. Accelerate for at least 2 seconds from valve pause mode.

- 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 during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.

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.