What this code means
P055D may mean the PCM is seeing the rocker arm oil pressure sensor B signal higher than expected.
What the vehicle may do
- The vehicle may turn on a warning light.
- Driveability symptoms may be mild or not obvious to the driver.
Possible fault areas
- Possible sensor signal circuit concern.
- Possible ground-side circuit concern.
- Possible connector or wiring concern.
- Possible PCM input concern after other checks are normal.
Diagnostic path
Open on P055D
For this Civic with the 2.0L non-turbo engine, P055D points to the PCM seeing the rocker arm oil pressure sensor B voltage higher than it expects. The driver may only notice a warning light, but the fault can involve the sensor signal path, the ground side, connector or wiring condition, or the PCM input after the rest of the circuit checks good. Treat this as an electrical sensor diagnosis: confirm the voltage fault first, then use the circuit checks to separate a sensor-side problem from a wiring or PCM-side problem.
Confirm the fault
Start with the basic system checks and follow a structured diagnostic approach. Turn the vehicle to the ON mode, then watch the HDS value for Rocker Arm Oil Pressure Sensor B Voltage. If that value is more than 4.79 V, the failure is duplicated. The logic behind the code is straightforward: when this sensor output voltage is higher than the specified value, the PCM judges it abnormal and stores P055D.
Check sensor output response
There is no direct bench-style test given for the sensor itself, so the path tests the related circuit response. Disconnect the rocker arm oil pressure sensor 3P connector. Then jumper terminals No. 1 and No. 2 at that connector, turn the vehicle to the ON mode, and check the HDS Rocker Arm Oil Pressure Sensor B Voltage again. Normal response here is less than 4.79 V. If the value responds normally with the jumper in place, the path points to a problem with the rocker arm oil pressure sensor. If it does not respond normally, keep going into the related circuit checks instead of guessing at the sensor.
Check SG1 and POIL for opens
Before disconnecting the PCM connector, jump the SCS line with the HDS and wait more than 1 minute. Then disconnect the rocker arm oil pressure sensor 3P connector and PCM connector E, the 80P connector. With IG Mode OFF, perform the SG1 open-wire inspection. The normal condition is less than 1 Ω. Then perform the POIL open-wire inspection, also with IG Mode OFF. The normal condition there is less than 1 Ω as well. If either circuit check is abnormal, the fault is in the circuit. Make sure the correct terminal callouts are confirmed before putting meter leads on the connectors; if the callouts are not clear, pause, recheck the earlier diagnostic path, and do not guess.
PCM conclusion
If the sensor response check and the SG1 and POIL open-wire checks all indicate a normal condition, then the remaining fault area in this diagnostic path is the PCM. At that point, call it a PCM problem only after those earlier checks have actually passed.
Verify and close
After the fault found in this path is corrected, keep verification separate from the circuit testing: verify the repair and confirm P055D stays gone. The takeaway is simple: duplicate the high-voltage reading, force the sensor circuit response, check SG1 and POIL for opens, and only then make the PCM call. For more diagnostic training, visit stepdiagnostics.com.
Final check
This code is often approached as an electrical sensor signal diagnosis: confirm the high reading, check circuit response, inspect the related wiring paths, then make the final module call only after a
For more guided automotive diagnostics, visit STEP Diagnostics.
