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DTC codes / P0Cxx · Hybrid propulsion / P0C0B

P0C0BDrive Motor A Inverter Power Supply Circuit/Open

P0C0B indicates that the hybrid or electric vehicle control module has detected an open circuit or power supply fault in the high-voltage inverter circuit that feeds drive motor A. The inverter converts direct current (DC) from the traction battery into alternating current (AC) for the motor, and this code means the inverter is not receiving the voltage it expects on its supply circuit.

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
  • The vehicle may enter a reduced power limp mode or refuse to start
  • Often no symptoms besides the warning light if the fault is intermittent
  • Loss of drive motor assistance or complete shutdown while driving
  • Audible relay clicking or no sound from the inverter at key-on
  • Reduced fuel economy on hybrid models due to disabled electric propulsion

Common causes, most likely first

  1. Blown high-voltage fuse or open fusible link in the inverter supply circuit
  2. Damaged or corroded wiring harness between the traction battery and inverter
  3. Loose or corroded connector pins at the inverter or battery junction box
  4. Failed inverter assembly internal power supply board
  5. Open circuit inside the high-voltage cable assembly
  6. Faulty battery pack junction board or service disconnect plug not fully seated
  7. Corrosion or water intrusion in the inverter supply connector

How to diagnose and fix it

  1. Perform a visual inspection of the high-voltage cables and connectors for damage or corrosion
  2. Check all related fuses and fusible links in the inverter supply path with a multimeter
  3. Disconnect the 12-volt battery and wait the specified time, then inspect and reseat the inverter high-voltage connectors
  4. Measure continuity and voltage drop across the supply circuit from the battery junction to the inverter
  5. Use a scan tool to check for other hybrid system codes and view live data for inverter supply voltage
  6. If the circuit tests good, perform the manufacturer's inverter diagnostic procedure, which may require high-voltage insulated tools
  7. Replace the faulty inverter or cable assembly only after confirming the open circuit location

High-Voltage Supply Faults Often Misdiagnosed

  • A loose service disconnect plug or a partially engaged high-voltage connector can set this code without any component failure.
  • Corrosion inside the inverter connector from road splash or condensation is a common cause that visual inspection alone may miss.
  • The code can be stored intermittently by a momentary voltage drop during cranking or a weak 12-volt battery, so always check the low-voltage system first.
  • Some vehicles set P0C0B when the inverter's internal capacitor fails to pre-charge, which mimics an open supply circuit but requires inverter replacement.
  • Do not assume the inverter is bad; a simple blown fuse in the battery junction box can produce identical symptoms and is far cheaper to fix.

Can I keep driving with P0C0B?

Do not continue driving with this code active, because the vehicle may lose propulsion without warning and high-voltage system faults can be dangerous. Have the vehicle towed to a qualified hybrid technician if it will not start or enters limp mode.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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

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