P0A6C

Code

Generic P — Powertrain

Drive Motor B Phase W Current

Brand: Generic

Type: P — Powertrain

Views: UK: 17 EN: 21 RU: 16

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Page language: EN

Causes

Open or short in phase W motor wiring (high-voltage cable, connector, terminal)
Faulty inverter/drive power module output stage for motor B phase W
Internal winding short or damage in Drive Motor B (phase W)
Defective current sensor or shunt associated with phase W
Corroded/loose high-voltage connector or poor contact/ground
Software/ECU fault or incorrect calibration (less common)

Symptoms

Malfunction Indicator Lamp (MIL) or hybrid/EV warning light illuminated
Reduced drive power, limp-mode, or limited torque availability
Loss of regenerative braking or reduced regen performance
Unusual motor noise, vibration, or smell from the motor/inverter area
Intermittent fault codes or faults that return after clearing

What to check

Retrieve full DTC list and freeze-frame data with a capable dealer/EV scan tool
Record live data: phase currents (U/V/W) for drive motor B, inverter output command, battery pack voltage and inverter temperature
Visually inspect high-voltage wiring, terminals, connectors and protective boots for damage, corrosion, melting or water intrusion
Check connectors are fully latched and locking tabs engaged; inspect for pin discoloration or burn marks
Compare phase currents: look for imbalance or one phase stuck near zero/current out-of-range
Verify 12V system and battery pack voltage are within spec

Signal parameters

Phase current nominal: near 0 A at idle/creep; rises under load — vehicle-specific (typically tens to hundreds of amps in EVs)
Phase-to-phase balance: currents should be similar under identical load; large deviation (e.g., >10–20%) indicates a fault
Current sensor output: may be a scaled CAN parameter or analog voltage from shunt — normally proportional to actual amps with near-zero at no-load
Inverter temperature: elevated temps can change current limits; refer to manufacturer limits

Diagnostic algorithm

Read and record all DTCs and freeze-frame data with an EV-capable scan tool; do not clear codes until initial inspection is complete.
Perform a visual inspection of the motor B high-voltage harness, inverter connections, and connectors associated with phase W. Repair obvious damage.
With appropriate PPE and isolation of high-voltage system, perform insulation resistance (megger) tests between each phase and vehicle ground and between phases to check for winding or insulation faults.
Using a suitable high-voltage clamp meter or the vehicle’s diagnostic live data, compare phase currents U/V/W during a controlled drive test or dynamometer run. Note any phase with no or excessive current.
Check continuity and resistance of phase W conductor back to the inverter output; measure for high resistance, opens, or shorts to other phases.
Inspect and, if possible, test the phase current sensor/shunt and its low-voltage measurement wiring or CAN messages. Replace/repair as indicated.
Monitor inverter module internal diagnostics (if supported) for failed output transistors or internal faults; consult manufacturer service data.
If wiring and sensors test good, consider motor bench test (motor removal) or inverter module replacement as directed by test results.
After repairs, clear codes and perform a full system verification including a road test and re-check for recurrence.

Likely causes

Damaged high-voltage cable or pin (water ingress, chafing)
Failed inverter MOSFET/IGBT leg driving phase W
Faulty phase current sensor/shunt or harness to the sensor
Internal motor B winding short or insulation failure
Poor high-voltage connector seating or terminal corrosion

Fault status

⚠️ Status

Drive Motor B Phase W current out-of-range or circuit fault detected. Possible wiring, current sensor, inverter output stage, or motor winding issue. Further diagnosis required.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 2-6 hours

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