P0C59
Drive Motor B Position Sensor Circuit A Intermittent/Erratic.
- Generic
- Powertrain
- Generic code
- High severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- C
- AreaHybrid propulsion
- 59
- FaultThe specific fault in that area
What it means
P0C59 is a generic powertrain code for hybrid and electric vehicles. It means the control unit has seen an intermittent or erratic signal from the position sensor (resolver or encoder) on drive motor B, circuit A. The signal drops out, jumps or does not match the expected rotor behaviour, so the motor control cannot rely on the rotor position reading.
Symptoms
- Warning lights on, such as the hybrid or EV system fault light or the main warning light
- Reduced power or the car going into a limited performance mode
- Intermittent loss of drive or hesitation under acceleration
- Rough running or vibration from the drive motor
- Engine not starting or failing to assist normally on a hybrid
- Fault that comes and goes, often with bumps or temperature changes
Possible causes
- Damaged, chafed or corroded wiring to the motor B position sensorlikely
- Loose, contaminated or poorly seated connector at the motor, inverter or control unitlikely
- Failing motor B position sensor (resolver or encoder)possible
- Electrical interference from damaged shielding or poor earthing on the sensor circuitpossible
- Mechanical problem such as incorrect sensor mounting or rotor damage affecting the signalrare
- Fault inside the inverter or motor control unitrare
How to diagnose
- Read all stored and pending codes and note the freeze frame data, including speed, motor temperature and when the fault occurred
- Check for other motor, inverter or low voltage supply codes that could point to a shared cause
- Following the manufacturer's high voltage safety procedure, which must only be carried out by a suitably trained person, inspect the sensor wiring and connectors for chafing, water, corrosion and bent or pushed-back pins
- Wiggle test the harness with live data on screen to see if the motor B position signal drops out or jumps
- Check the low voltage battery condition and earth connections, as poor supply can cause erratic signals
- Test the sensor circuit resistance and continuity, and the shielding, against the manufacturer's specification for the model
- Check the sensor and its mounting for damage or movement, as the procedure varies by model
- Check for software updates or technical bulletins for the model before condemning the control unit
How to fix
- Repair or replace damaged wiring and restore the shielding
- Clean, repair or replace faulty connectors and terminals
- Replace the motor B position sensor or motor assembly if testing shows it is faulty
- Repair poor earth or supply faults on the low voltage system
- Replace or repair the inverter or control unit only after the wiring and sensor have been proven good
- Apply a manufacturer software update if an outdated calibration is a known cause for that model
Can I keep driving?
High severity
Limit driving, as the car may lose drive or power without warning, which is a safety risk in traffic. Have it checked by a trained hybrid or EV technician as soon as possible.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.