What Does P0C05 Mean?
This code indicates an open circuit condition or general circuit fault in the Drive Motor A three-phase power circuit (Phase U, V, and W collectively). Unlike the individual phase current sensor codes, this fault relates to the actual power delivery path between the inverter and the motor windings. An open circuit means one or more phases cannot conduct current, completely preventing motor operation or causing severe torque pulsation.
Safety Warning
An open phase circuit completely disables Motor A or causes dangerous single-phase operation with severe torque pulsation. The vehicle cannot be safely driven. High-voltage components must only be serviced by qualified technicians with proper PPE. Have the vehicle towed.
Common Causes
30%
Loose or corroded high-voltage phase conductor connection at the motor or inverter
25%
Motor A stator winding open circuit (broken conductor) in one phase
20%
Inverter power stage failure (open IGBT/MOSFET) on one or more phases
15%
High-voltage phase cable damage or disconnection between inverter and motor
10%
Motor A phase terminal insulation failure causing a controlled disconnect by the safety system
Diagnostic Steps
1
Retrieve freeze-frame data to determine if the open circuit occurred suddenly (catastrophic failure) or was detected during a startup self-test.
2
With the high-voltage system properly de-energized and safety-locked, inspect all three phase conductor connections at both the Motor A terminal box and the inverter output.
3
Measure continuity through each phase from the inverter output terminal through the cable to the motor terminal — an infinite reading identifies the open phase.
4
Measure Motor A phase winding resistances at the motor terminal box to identify if the open circuit is internal to the motor.
5
If phase cables and motor windings have continuity, the fault is likely in the inverter power stage — check each IGBT/MOSFET for open-circuit failure mode.
6
Inspect the high-voltage interlock loop (HVIL) connectors on the Motor A circuit for proper engagement.
Estimated Repair Cost
$500 - $5,000
Parts + labor, varies by vehicle and location
This code indicates an open circuit condition or general circuit fault in the Drive Motor A three-phase power circuit (Phase U, V, and W collectively). Unlike the individual phase current sensor codes, this fault relates to the actual power delivery path between the inverter and the motor windings. ...
The most common cause of P0C05 (Drive Motor "A" Phase U-V-W Circuit/Open) is: Loose or corroded high-voltage phase conductor connection at the motor or inverter
Typical repair costs for P0C05 range from $500 to $5,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
An open phase circuit completely disables Motor A or causes dangerous single-phase operation with severe torque pulsation. The vehicle cannot be safely driven. High-voltage components must only be serviced by qualified technicians with proper PPE. Have the vehicle towed.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0C05 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Hybrid/EV Drive Motor System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
