Damaged, chafed or corroded wiring in the motor position sensor circuit (short to earth or open circuit); Poor connection or water ingress at the motor position sensor connector or inverter connector; Faulty drive motor B position sensor (resolver or equivalent); Sensor supply or reference voltage fault; Fault within the inverter or motor control unit; Mechanical damage to the motor or sensor mounting affecting the signal.

P0C57

Drive Motor B Position Sensor Circuit A Low.

Generic
Powertrain
Generic code
High severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
C: AreaHybrid propulsion
57: FaultThe specific fault in that area

What it means

P0C57 is a generic powertrain code relating to the position sensor circuit for drive motor B on a hybrid or electric vehicle. The motor control unit saw the signal voltage from the sensor circuit fall below the expected range, so it can no longer trust the rotor position reading. Exact sensor type, circuit naming and set conditions vary by manufacturer and model.

Symptoms

Warning lights on, such as the hybrid system or malfunction indicator
Reduced power or limp-home mode
Vehicle will not enter Ready mode or will not move
Rough, jerky or noisy motor operation
Sudden loss of drive or shutdown while driving
Reduced regenerative braking or hybrid assist

Possible causes

Damaged, chafed or corroded wiring in the motor position sensor circuit (short to earth or open circuit)likely
Poor connection or water ingress at the motor position sensor connector or inverter connectorlikely
Faulty drive motor B position sensor (resolver or equivalent)possible
Sensor supply or reference voltage faultpossible
Fault within the inverter or motor control unitrare
Mechanical damage to the motor or sensor mounting affecting the signalrare

How to diagnose

Read all stored codes and freeze frame data, noting whether other drive motor or inverter codes are present and under what conditions it set.
Check for technical service bulletins and known issues for the specific model and motor B arrangement.
Visually inspect the sensor wiring and connectors for chafing, heat damage, corrosion, moisture and bent or pushed-back pins, following the manufacturer's high-voltage safety procedure.
Check the 12 V battery condition and charging, as low supply voltage can cause circuit faults.
With the system safely shut down, test the sensor circuit for continuity, short to earth and resistance against the manufacturer's specification.
Check the sensor's own resistance or signal against specification, as the method depends on the model.
Monitor live position sensor data while the system is operating, and wiggle-test the harness to look for dropouts.
Only after wiring and sensor are proven good, consider testing the inverter or motor control unit per the manufacturer's procedure.

How to fix

Repair or replace damaged wiring in the sensor circuit.
Clean, repair or replace corroded or loose connectors, and seal out any water ingress.
Replace the drive motor B position sensor if it is out of specification, following the manufacturer's procedure.
Restore correct supply or reference voltage by repairing the fault that is causing it.
Repair or replace the inverter or motor control unit only if confirmed faulty, with any required programming per the manufacturer.

Can I keep driving?

High severity

Avoid driving, as loss of motor position data can cause sudden power loss or a failure to move. Have the car checked by someone qualified to work on high-voltage systems before further use.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.