DTC Advanced Diagnostics: P2656
DTC P2656:Rocker Arm Oil Pressure Switch A (Bank 2) Circuit Low Voltage

General Description
With VCM

Mode
PCM sends command to the rocker arm oil control solenoid
Rocker arm oil pressure switch
(detected oil pressure)
Solenoid A (Bank 1)
Solenoid B (Bank 1)
Solenoid A (Bank 2)
Switch A (Bank 1)
Switch B (Bank 1)
Switch A (Bank 2)
6 Cylinder Mode
(Low VTEC Range)
OFF
OFF
OFF
ON (low)
OFF (low)
ON (low)
6 Cylinder Mode
(High VTEC Range)
ON
OFF
ON
OFF (high)
OFF (low)
OFF (high)
3 Cylinder Mode
(3 Cylinders are paused)
OFF
ON
OFF
ON (low)
ON (high)
ON (low)

Without VCM

Mode
PCM sends command to the rocker arm oil control solenoids
Rocker arm oil pressure switch
(detected oil pressure)
Solenoid A
(Bank 1)
Solenoid A
(Bank 2)
Switch A (Bank 1)
Switch A (Bank 2)
Low VTEC Range
OFF
OFF
ON (low)
ON (low)
High VTEC Range
ON
ON
OFF (high)
OFF (high)

The VTEC system activates the rocker arm oil control solenoid A (bank 2) with a command from the powertrain control module (PCM), and it charges/discharges the hydraulic circuit of the VTEC mechanism that switches valve timing between Low and High. The PCM monitors oil pressure in the hydraulic circuit of the VTEC mechanism using the rocker arm oil pressure switch A (bank 2) downstream of the rocker arm oil control solenoid A (bank 2). 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 switch A (bank 2), the system is considered faulty, and a DTC is stored.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status
Execution
Once per driving cycle
Sequence
None
Duration
A/T model
3.0 seconds or more
Duration
M/T model
7.0 seconds or more
DTC Type
One drive cycle, MIL on
OBD Status
PASSED/FAILED/NOT COMPLETED (STILL TESTING)

Enable Conditions
Condition
Minimum
Maximum
Engine Coolant temperature
[ECT SENSOR 1]
50 °F (10 °C)
–
Engine speed [ENGINE SPEED]*
A/T model
5,150 rpm
–
M/T model
4,900 rpm
–
Vehicle speed
[VEHICLE SPEED]
7 mph (10 km/h)
–
Battery voltage [BATTERY]
10.5 V
–
Shift lever position*1
Other than P or N
No active DTCs set (prevents monitor from running)
P2658, P2659
*: Variable that is depending on the engine load.

*1: A/T model

[ ]: HDS Parameter

Malfunction Threshold
When the rocker arm oil control solenoid A (bank 2) is ON, the rocker arm oil pressure switch A (bank 2) remains ON.

Logic Decision
Rocker Arm Oil Pressure Switch A (Bank 2)
ON
OFF
Rocker Arm Oil Control Solenoid A (Bank 2) Command
ON
Failure (P2656)
Normal
OFF
Normal
Failure (P2657)

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 A (bank 2) failure
Rocker arm oil control solenoid A (bank 2) VTSB2 line open
Rocker arm oil control solenoid A (bank 2) VTSB2 line short
Rocker arm oil pressure switch A (bank 2) failure
Rocker arm oil pressure switch A (bank 2) VTMB2 line open
Rocker arm oil pressure switch A (bank 2) VTMB2 line short
Oil passage clogged

Confirmation Procedure
Operating Condition
1.
Start the engine. Hold the engine speed [ENGINE SPEED] at 3,000 rpm without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.
2.
Drive the vehicle at an engine speed [ENGINE SPEED] 5,150 rpm or more for at least 3*1 (7)*2 seconds.

*2: M/T model
Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
With the HDS
With VCM: Select the VTEC+VCM TEST in the INSPECTION MENU with the HDS, then select the VEB VTEC TEST with the HDS.

Without VCM: Select the VTEC TEST in the INSPECTION MENU with the HDS.

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 PCM 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.