What Does P0C0B Mean?
DTC P0C0B indicates an open circuit or general malfunction in the power supply feeding the drive motor "A" inverter. The inverter requires a stable high-voltage DC supply from the traction battery to convert it into three-phase AC for the motor. An open in this circuit means the inverter cannot operate, resulting in complete loss of electric propulsion from motor "A". This is a critical fault that will activate failsafe mode immediately.
Safety Warning
Complete loss of electric drive from motor "A" will severely limit or eliminate propulsion. In a pure EV, the vehicle may be inoperable. In a hybrid, it may revert to engine-only mode with degraded performance. HV circuits require trained technicians with appropriate PPE.
Common Causes
30%
Open or blown HV fuse in the inverter supply circuit
25%
Damaged or disconnected HV cable between battery junction box and inverter
20%
Corroded or overheated HV connector at the inverter input
15%
Failed HV battery contactor not closing properly
10%
Internal inverter pre-charge circuit failure
Diagnostic Steps
1
Step 1: Check for related DTCs including battery contactor codes, HV interlock codes, and pre-charge circuit codes. Review freeze-frame data for battery SOC, HV bus voltage, and contactor status.
2
Step 2: Verify the HV battery system is commanding the main contactors closed. Check the battery management system for any isolation faults or contactor welding/open faults.
3
Step 3: With appropriate HV safety procedures, inspect the HV fuse(s) in the inverter supply circuit. Check for blown fuse elements and measure continuity.
4
Step 4: Inspect all HV connectors between the battery pack, junction box, and inverter module for signs of overheating, arcing, corrosion, or incomplete seating. Verify the HV interlock circuit is intact.
5
Step 5: Measure the DC bus voltage at the inverter input terminals (with HV-rated equipment) while the contactors are commanded closed. Compare with the battery pack voltage — a significant difference indicates a wiring or connection fault.
6
Step 6: If all external circuits test normal, the inverter pre-charge relay or internal bus capacitor circuit may have failed. Replace the inverter per manufacturer procedure.
Estimated Repair Cost
$500 - $6,000
Parts + labor, varies by vehicle and location
DTC P0C0B indicates an open circuit or general malfunction in the power supply feeding the drive motor "A" inverter. The inverter requires a stable high-voltage DC supply from the traction battery to convert it into three-phase AC for the motor. An open in this circuit means the inverter cannot oper...
The most common cause of P0C0B (Drive Motor "A" Inverter Power Supply Circuit/Open) is: Open or blown HV fuse in the inverter supply circuit
Typical repair costs for P0C0B range from $500 to $6,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Complete loss of electric drive from motor "A" will severely limit or eliminate propulsion. In a pure EV, the vehicle may be inoperable. In a hybrid, it may revert to engine-only mode with degraded performance. HV circuits require trained technicians with appropriate PPE.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0C0B to identify the root cause.
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Quick Info
Category
Powertrain
System
Hybrid/EV Drive Motor Inverter
Difficulty
Type
Generic (SAE)
Recommended Tools
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