DTC P2646
DTC P2646: Rocker Arm Oil Pressure System Stuck Off
General Description
| Logic Decision | Rocker Arm Oil Pressure Switch | |
|---|---|---|
| 'Lo' | 'Hi' | |
| Rocker Arm Oil Control Solenoid Command 'ON' | Failure | Normal |
| Rocker Arm Oil Control Solenoid Command 'OFF' | Normal | Failure |
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 | 7 seconds or more |
| DTC Type | Two drive cycles, MIL on |
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| Engine coolant temperature [ECT Sensor 1] | 50 deg.F (10 deg.C) | - |
| Engine speed [Engine Speed]* | 990 rpm | - |
| Vehicle speed [Vehicle Speed] | 0 mph (0 km/h) | - |
| 12 volt battery voltage [Battery] | 10.5 V | - |
| Other | Other than wide open throttle | |
*: Variable that is depending on the engine load.
[ ]: HDS Parameter
Malfunction Threshold
When the rocker arm oil control solenoid is ON, the rocker arm oil pressure sensor output remains low (49 kPa (0.49 kgf/cm 2, 7.1 psi) or less).
Possible Cause
NOTE: 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 control solenoid VTS line open
- Rocker arm oil control solenoid VTS line short
- Rocker arm oil pressure sensor output stuck
- Rocker arm oil control solenoid failure
- Oil passage clogged
Confirmation Procedure
Operating Condition
- Enter the maintenance mode, then start the engine, and let it idle until the radiator fan comes on.
- Drive the vehicle at an engine speed [ENGINE SPEED] 990 rpm or more for at least 7 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 Menu 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 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 12 volt battery.