P0C03: Drive Motor B Current Low

P0C03 indicates that drive motor B draws less current than the controller expects for the requested torque. It is the low counterpart of P0C04 and the motor B twin of P0C00. No manufacturer documents this exact code publicly, and the GM hybrid tables use only P0C04 and P0C08 for motor B. CARB requires hybrids to monitor electric motor performance. Low current typically comes from a high-resistance cable joint, an interrupted winding path or an inverter stage that does not switch; a single missing phase is reported by GM as P0C08. In practice motor B delivers little or no torque, a warning lamp lights up and the system may fall back to the other motor or the engine.

Symptoms

• Weak or missing torque from motor B
• Warning lamp for the hybrid or electric drive
• Reduced performance or limp mode

Most likely causes

• High-resistance or loose three-phase connection of motor B
• Inverter power stage for motor B not delivering current
• Open or damaged winding in drive motor B

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 P0C03 means

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

Frequently asked questions

Can I keep driving with code P0C03?

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 P0C03?

The most common causes are: high-resistance or loose three-phase connection of motor B; inverter power stage for motor B not delivering current; open or damaged winding in drive motor B.

Related codes

• P0C02Drive Motor B Current
• P0C04Drive Motor B Current High
• P0C00Drive Motor A Current Low
• P0C08Drive Motor B Phase U-V-W Circuit/Open
• P0BFEDrive Motor B Phase U-V-W Current Sensor Correlation
• P0A79Drive Motor B Inverter Performance

Sources

• law.cornell.edu: 13 CCR 1968.2
• gsi.ext.gm.com: 12OBDG06 Hybrid Diagnostics
• static.nhtsa.gov: MC 11029775 0001

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.