P0C0B — Drive Motor “A” Inverter Power Supply Circuit/Open #

Note: The code description may vary depending on the vehicle manufacturer. Always refer to your OEM (Original Equipment Manufacturer) documentation for model-specific information.

• Toyota/Lexus: Drive Motor “A” Inverter Power Supply Circuit/Open
• Honda/Acura: Drive Motor “A” Inverter Power Supply Circuit Malfunction
• Nissan/Infiniti: Drive Motor A Inverter Power Supply Circuit/Open
• General Motors (GM): Drive Motor ‘A’ Inverter Power Supply Circuit Open

Summary of the P0C0B code #

The P0C0B code indicates an issue with the power supply circuit or an open circuit in the inverter system for Drive Motor “A” in hybrid or electric vehicles. The inverter is the critical component that converts DC (Direct Current) battery power into AC (Alternating Current) for the drive motors. When the power supply circuit to the inverter or its connections are interrupted or malfunctioning, the vehicle’s onboard computer (ECU) flags this code. This is a serious issue, as the drive motor is essential for propulsion in hybrid and electric vehicles. The code is most commonly seen in vehicles using high-voltage hybrid systems.

Common symptoms for code P0C0B #

When the P0C0B code is present, your vehicle may display a range of symptoms, most of which relate to reduced or lost propulsion and electrical anomalies. You may notice:

• Illuminated Check Engine Light or hybrid system warning indicator
• Reduced engine or motor power (“limp mode”)
• Failure to start or move the vehicle (in extreme cases)
• Battery or EV system warning messages on the dashboard
• Unusual noises from the inverter or drive motor area
• Loss of regenerative braking capability

Probable causes for code P0C0B (by frequency) #

The underlying causes for P0C0B generally relate to electrical or electronic faults in high-voltage components. Below are the most frequent culprits, ordered by likelihood:

1. Faulty inverter assembly (internal failure or damaged power supply circuit)
2. Open or damaged wiring harness between inverter and drive motor
3. Loose, corroded, or unplugged electrical connectors at the inverter or control module
4. Failed drive motor “A” (in rare cases, the motor itself has an electrical fault)
5. Defective inverter coolant pump (causing inverter overheating and circuit failure)
6. Blown fuse or relay in the inverter power circuit
7. Faulty HV ECU (High Voltage Electronic Control Unit)

Step-by-step diagnostic for code P0C0B #

Diagnosing a P0C0B code requires careful safety precautions due to the high-voltage systems involved. Only qualified technicians should perform these steps:

1. Read and record all codes with an OBD-II/EOBD scan tool, and note any related DTCs.
2. Visually inspect the inverter assembly, wiring harnesses, and connectors for signs of damage, corrosion, or loose connections.
3. Check inverter fuses and relays for continuity and correct operation.
4. Test inverter coolant pump operation to ensure it is running and the inverter is not overheating.
5. Measure voltage and continuity in the inverter power supply circuit (using manufacturer procedures and proper high-voltage precautions).
6. Check for technical service bulletins (TSBs) related to inverter or hybrid system issues for your specific vehicle.
7. Replace or repair any faulty components as identified above, then clear codes and test drive to confirm resolution.

Possible repairs for code P0C0B #

Depending on the root cause, repairs for P0C0B can range from simple electrical fixes to major component replacements. The most common solutions are:

• Repairing or replacing damaged wiring or connectors in the inverter circuit
• Replacing a faulty inverter assembly
• Replacing a defective drive motor “A” (rare)
• Replacing a failed inverter coolant pump
• Replacing blown fuses or faulty relays in the high-voltage system
• Addressing control module faults (reprogramming or replacing the HV ECU if needed)

Is it safe to drive with code P0C0B? #

No, it is usually not safe to drive with this code present. The inverter power supply circuit is central to hybrid and electric vehicle operation. Loss of inverter function can result in sudden propulsion loss, inability to restart, or dangerous limp mode driving. Continuing to drive may cause further damage to high-voltage components. If the vehicle operates at all, it should be moved only to a safe location or directly to a qualified repair facility.

Vehicles most commonly affected by code P0C0B #

This code is most frequently seen in hybrid and electric vehicles that use a high-voltage inverter to power the main drive motor. Models known to experience P0C0B include:

• Toyota Prius (all generations, especially Gen 2 and Gen 3)
• Lexus CT200h, ES300h, RX450h
• Nissan Leaf
• Honda Accord Hybrid, Insight
• Chevrolet Volt
• Hyundai Ioniq Hybrid/Electric
• Kia Niro Hybrid/Electric

Common mistakes & best practices with code P0C0B #

Misdiagnosis or hasty repair attempts can lead to further problems or safety hazards. Keep these tips in mind:

• Do not touch high-voltage components without proper training and equipment
• Always disconnect the high-voltage battery per OEM procedure before inspecting or repairing the inverter system
• Do not simply clear the code without fixing the root cause—it will return and may trigger worse symptoms
• Do not replace the inverter without first checking for wiring or connector faults
• Always check for OEM technical service bulletins—some vehicles have known issues or extended warranties on inverter parts

Quick FAQ for code P0C0B #

Here are answers to common questions about P0C0B:

• Q: Can a weak 12V battery cause P0C0B?
  A: Rarely. P0C0B relates to the high-voltage inverter circuit, not the low-voltage (12V) system. However, a very low 12V battery can sometimes cause hybrid system initialization errors.
• Q: I replaced the inverter, but the code came back. What else should I check?
  A: Inspect all related wiring, connectors, fuses, and the inverter coolant pump. It’s common for wiring damage or a failed pump to mimic inverter failure.