DTC P2651
DTC P2651: Rocker Arm Oil Pressure Stuck Off
General Description
| Logic Decision | Rocker Arm Oil Pressure Sensor | |
|---|---|---|
| Low Oil Pressure (Oil pressure < Threshold) | High Oil Pressure (Oil pressure > Threshold) | |
| Rocker Arm Oil Control Solenoid Command "ON" | Failure (P2651) | Normal |
| Rocker Arm Oil Control Solenoid Command "OFF" | Normal | Failure (P2652) |
The VTEC system activates the rocker arm oil control solenoid with a command from the powertrain control module (PCM), and it charges/discharges the hydraulic circuit of the VTEC mechanism that delays valve timing. The PCM monitors oil pressure in the hydraulic circuit of the VTEC mechanism using the rocker arm oil pressure sensor downstream of the rocker arm oil control solenoid.
If there is a difference between the oil pressure condition in the hydraulic circuit determined by the PCM command and the oil pressure condition determined by the status of the rocker arm oil pressure sensor, the system is considered faulty, and a DTC is stored.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Once per driving cycle |
| Sequence | None |
| Duration | 16 seconds or more |
| DTC Type | Two drive cycles, MIL on |
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| Engine coolant temperature [ ECT Sensor 1 ] | 140 deg.F (60 deg.C) | - |
| Engine speed [ Engine Speed ] | 1000 RPM | - |
| Vehicle speed [ Vehicle Speed ] | 10 mph (15 km/h) | - |
| 12 volt battery voltage [ Battery ] | 10.5 V | - |
| Shift position/mode | Other than P or N | |
| [ ] : HDS Parameter | ||
Malfunction Threshold
When the rocker arm oil control solenoid is ON, the rocker arm oil pressure sensor output remains low (40.0 kPa (0.40 kgf/cm2 , 5.8 psi) or less).
Possible Cause
The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
- Rocker arm oil pressure sensor P-OIL line open
- Rocker arm oil pressure sensor P-OIL line short
- Oil passage clogged
- Rocker arm oil control solenoid failure
Confirmation Procedure
Operating Condition
- Start the engine. Hold the engine speed [ Engine Speed ] at 3000 RPM without load (in P or N) until the radiator fan comes on, then let it idle.
- Drive the vehicle at a steady speed of 10 mph (15 km/h) or more and engine speed [ Engine Speed ] 1150 RPM or more for at least 16 seconds.
- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
With the HDS
Select the VTEC TEST in the Function Test with the HDS.
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, the freeze data, and the on-board snapshot 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, the freeze data, and the on-board snapshot can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.