P0C6B

What it means

P0C6B means the hybrid or electric drive control unit has seen the signal from generator position sensor circuit B (the resolver that reports generator rotor angle) below its expected voltage range. The control unit needs this signal to time the generator's current correctly. Exact wiring, sensor layout and which machine is 'generator B' depend on the vehicle and drivetrain.

Symptoms

• Hybrid or powertrain warning light on
• Reduced power or limp-home mode
• Engine or hybrid system fails to start or shuts down unexpectedly
• Poor or rough running when the engine and generator are working together
• Hybrid battery not charging properly or erratic charge/discharge behaviour

Possible causes

• Damaged, chafed or shorted wiring in the generator position sensor circuit B (signal shorted to ground or open circuit)likely
• Corroded, loose or water-contaminated connector at the generator, inverter or control unitlikely
• Faulty generator position sensor (resolver) or incorrect sensor alignment after repairpossible
• Fault inside the inverter or motor/generator control unit's sensor interfacepossible
• Low or unstable supply or reference voltage to the sensor circuitpossible
• Internal generator winding or housing damage affecting the sensorrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting whether other hybrid, inverter or generator codes are present.
2. Check for technical service bulletins and model-specific procedures for this code, as the circuit layout varies by vehicle.
3. Visually inspect the generator position sensor wiring and connectors for chafing, heat damage, corrosion, moisture and pushed-back pins.
4. Observe the generator speed or position data on a live data display while the system runs, and look for dropouts or implausible values.
5. Only if you are trained and qualified for high-voltage systems, make the system safe, then check the sensor circuit for continuity, short to ground and resistance against the manufacturer's specification.
6. Check the sensor's resistance or signal against specification, following the model-specific procedure.
7. Wiggle-test the harness with live data running to find intermittent faults.
8. Check the inverter and control unit supply, earths and reference voltages before condemning the control unit.

How to fix

• Repair or replace damaged wiring in the generator position sensor circuit B.
• Clean, repair or replace corroded or damaged connectors and fix any water ingress.
• Replace the generator position sensor or generator assembly if it is out of specification, setting alignment as the manufacturer requires.
• Repair supply or earth faults affecting the sensor circuit.
• Replace or repair the inverter or control unit only after confirming the wiring and sensor are good, and apply any required software update.

Can I keep driving?

Nearby codes

• P0C6AGenericGenerator Position Sensor Circuit B Range/Performance
• P0C6CGenericGenerator Position Sensor Circuit B High