What this code means

The belt-driven starter-generator (BSG) is not producing expected torque output for engine starting, boost assist, or energy recovery.

Symptoms

• Slow engine cranking
• No electric torque assist
• Weak regenerative braking
• Increased fuel consumption
• Belt squeal during start
• Vibration during BSG operation

Common causes

• BSG internal fault
• Drive belt slip
• Belt tensioner wear
• BSG bearing failure
• Inverter module fault

Diagnostic steps

1. Check BSG torque output via scan tool
2. Inspect drive belt condition and tension
3. Listen for BSG bearing noise
4. Test BSG inverter module
5. Monitor BSG temperature during operation

Repair notes

Replace BSG unit if internal fault confirmed. Replace drive belt and tensioner if slipping. BSG and belt are a common service item together.

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