Damaged or chafed wiring in the motor position sensor harness, especially near connectors or heat sources; Corroded, loose, or water-intruded electrical connector at the position sensor or control module; Failed motor position sensor (circuit A element) due to internal wear or thermal damage; Faulty hybrid or electric vehicle control module with an internal driver or signal-conditioning fault; Mechanical damage to the sensor reluctor or tone ring inside the motor assembly; Electrical interference or a poor ground connection affecting the sensor reference voltage; Aftermarket or improperly installed components that disturb the sensor signal circuit

DTC codes / P0Cxx · Hybrid propulsion / P0C55

P0C55Drive Motor B Position Sensor Circuit A Circuit

Q: What does code P0C55 mean?

Drive Motor B Position Sensor Circuit A Circuit. P0C55 indicates that the hybrid or electric vehicle control module has detected an abnormal signal from the position sensor circuit for drive motor B, specifically the channel designated as circuit A. This sensor reports the rotor position of the traction motor, and the module uses that data to synchronize motor commutation and verify safe operation. The code is set when the voltage or signal pattern on circuit A falls outside the expected range or becomes inconsistent with the other position sensor channels.

P0C55 indicates that the hybrid or electric vehicle control module has detected an abnormal signal from the position sensor circuit for drive motor B, specifically the channel designated as circuit A. This sensor reports the rotor position of the traction motor, and the module uses that data to synchronize motor commutation and verify safe operation. The code is set when the voltage or signal pattern on circuit A falls outside the expected range or becomes inconsistent with the other position sensor channels.

SystemPowertrain

Code typeGeneric (all makes)

SeverityHigh

Fix difficultyProfessional

AreaHybrid propulsion

Symptoms you may notice

Illumination of the hybrid system warning light or service vehicle soon message
Often no symptoms besides the warning light, with the vehicle continuing to drive normally
Reduced power or a limp-home mode that limits motor output
Rough operation or shuddering during acceleration or regenerative braking
The vehicle may refuse to start or shift into gear if the fault is severe
Intermittent stalling or sudden loss of propulsion while driving

Common causes, most likely first

Damaged or chafed wiring in the motor position sensor harness, especially near connectors or heat sources
Corroded, loose, or water-intruded electrical connector at the position sensor or control module
Failed motor position sensor (circuit A element) due to internal wear or thermal damage
Faulty hybrid or electric vehicle control module with an internal driver or signal-conditioning fault
Mechanical damage to the sensor reluctor or tone ring inside the motor assembly
Electrical interference or a poor ground connection affecting the sensor reference voltage
Aftermarket or improperly installed components that disturb the sensor signal circuit

How to diagnose and fix it

Perform a visual inspection of the motor position sensor harness and connectors for chafing, corrosion, or loose pins
Check for technical service bulletins (TSBs) or manufacturer communications specific to this code and vehicle platform
Measure the sensor circuit A signal with an oscilloscope and compare it to the expected waveform from the service information
Verify the sensor reference voltage and ground at the sensor connector with a digital multimeter
Perform a wiggle test on the harness while monitoring live data to expose intermittent faults
Replace the motor position sensor if the signal is erratic or absent and wiring is confirmed good
If the sensor and wiring test good, diagnose or replace the hybrid control module as the last step

What the position sensor circuit really tells you

A common misdiagnosis is replacing the motor position sensor when the actual fault is a chafed wire inside the harness loom, so always perform a loaded wiggle test before condemning the sensor.
The code can set intermittently from a poor ground connection at the motor housing, which corrupts the sensor reference voltage without any visible wiring damage.
Some vehicles will set P0C55 after a low-voltage event or battery replacement, and the code may clear after a successful relearn procedure rather than a parts replacement.
The position sensor circuit A is one channel of a multi-channel resolver or encoder, and a fault in one channel can mimic a mechanical motor problem, so compare all channels on a scope.
Aftermarket inverters or unauthorized software modifications can disturb the sensor signal and set this code even when all hardware is functioning correctly.

Can I keep driving with P0C55?

Do not continue driving with this code if the vehicle is in limp mode or shows reduced power, because a failed position sensor can cause sudden loss of propulsion. If the only symptom is the warning light and the vehicle drives normally, arrange a diagnostic appointment promptly and avoid heavy acceleration or high-speed driving until repaired.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.