P0C06: Drive Motor A Phase U-V-W Circuit Low

P0C06 belongs to the phase circuit group of drive motor A and reports that a U, V or W phase line sits too low, typically a short to the negative high-voltage rail or to chassis ground. P0C05 covers an open or missing phase, P0C07 the opposite high state. No manufacturer documents P0C06 for a drive motor publicly; GM's hybrid tables use only P0C05 from this trio. CARB requires hybrid input and output components to be monitored for circuit faults. Such a short usually also trips the inverter's overcurrent protection, so P0C01 or insulation faults may appear alongside. The motor controller shuts down motor A, which leaves the driver with reduced or no electric drive and a warning lamp.

Symptoms

• Electric drive shut down with warning lamp
• Overcurrent or insulation codes stored at the same time

Most likely causes

• Phase cable or winding shorted to ground or housing
• Shorted low-side power switch in the motor A inverter
• Insulation damage from heat, moisture or chafing

What to check, in order

Start with the simplest. You can tick off each step.

1. Read the codes with a hybrid-compatible scanner and write down the freeze frame data
2. With the connector unplugged, check whether the signal wire is making contact with ground.
3. Make sure the battery cooling air intake is clean
4. Check the 12 V auxiliary battery, which can also trigger warnings
5. Leave any high-voltage measurements to a specialized repair shop

Good to know

• It can trigger limp mode.
• It affects emissions.

What each character of P0C06 means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• C: Subsystem depends on the code range
• 06: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0C06?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0C06?

The most common causes are: phase cable or winding shorted to ground or housing; shorted low-side power switch in the motor A inverter; insulation damage from heat, moisture or chafing.

Related codes

• P0C05Drive Motor A Phase U-V-W Circuit/Open
• P0C07Drive Motor A Phase U-V-W Circuit High
• P0C09Drive Motor B Phase U-V-W Circuit Low
• P0C01Drive Motor A Current High
• P0BFDDrive Motor A Phase U-V-W Current Sensor Correlation

Sources

• law.cornell.edu: 13 CCR 1968.2
• gsi.ext.gm.com: 12OBDG06 Hybrid Diagnostics

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.