P0C68

What it means

P0C68 is the SAE J2012 generic code for an intermittent or erratic signal in the generator position sensor circuit A. The generator is the motor-generator used in hybrid and electrified drivetrains, and its position sensor (often a resolver) tells the control unit the rotor angle. The control unit saw the signal drop out, jump or become implausible from time to time, rather than fail completely.

Symptoms

• Hybrid or powertrain warning light on, possibly with a ready-system fault message
• Intermittent loss of power or the car going into a reduced-power mode
• Engine failing to start or stalling, particularly on hybrid systems that crank the engine using the generator
• Poor or erratic hybrid battery charging and unusual fuel economy
• Symptoms that come and go, often linked to bumps, heat or vibration

Possible causes

• Loose, corroded or damaged connector at the generator position sensor or at the control unitlikely
• Chafed, stretched or broken wiring in the sensor circuit, causing an intermittent open, short or crosstalklikely
• Failing generator position sensor (resolver) with an intermittent internal faultpossible
• Moisture, coolant or oil contamination in the generator housing or connectorpossible
• Electrical interference from damaged shielding or poor earthing in the high-voltage or signal wiringpossible
• Fault in the hybrid or motor control unit, or an outdated calibration where the manufacturer has issued a fixrare

How to diagnose

1. Read all stored and pending codes and record the freeze frame data, noting speed, temperature and whether the fault occurred at start-up or while driving
2. Check for related codes covering the generator, motor, inverter or other position sensors, as these point towards a common cause
3. Look up manufacturer technical bulletins and calibration updates for the specific model and engine
4. Visually inspect the sensor wiring and connectors for chafing, corrosion, bent pins, water ingress and poor terminal tension; follow the manufacturer's high-voltage safety procedure and do not touch orange high-voltage cabling unless qualified
5. Wiggle-test the harness and connectors with live data on screen to see if the sensor signal drops out or becomes erratic
6. Check the circuit for continuity, short to earth, short to supply and resistance against the manufacturer's specification, with the system safely isolated
7. Measure the sensor's coil resistance or signal against specification, which varies by model, and check for contamination in the housing
8. Check earths and shielding continuity for the sensor circuit

How to fix

• Clean, repair or replace faulty connectors and terminals and secure the harness
• Repair or replace damaged wiring in the sensor circuit, restoring any shielding
• Replace the generator position sensor or the generator assembly if the sensor is not serviced separately, as the model dictates
• Find and cure the source of moisture or fluid leakage, then dry or replace affected components
• Repair earth or shielding faults causing interference
• Update or replace the control unit calibration or unit only if diagnosis or a manufacturer bulletin confirms it as the cause

Can I keep driving?

Nearby codes

• P0C67GenericGenerator Position Sensor Circuit A High
• P0C69GenericGenerator Position Sensor Circuit B