P0A6B

Code

Generic P — Powertrain

Drive Motor B Phase V Current High

Brand: Generic

Type: P — Powertrain

Views: UK: 24 EN: 36 RU: 22

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Page language: EN

Causes

Faulty/internally shorted inverter power module (IGBT/MOSFET) on Motor B phase V
Short or low-resistance fault in Motor B phase V winding (internal motor short)
Short to chassis or battery in phase V wiring or connector
Open, corroded, or damaged phase wiring/connector causing abnormal currents or sensor misreading
Failed or out-of-spec phase current sensor / sensing resistor / current clamp for Motor B
Control module software or calibration fault reporting incorrect current

Symptoms

Malfunction indicator lamp / EV system warning illuminated
Reduced drive power, limp mode, or drive disabled
Unusual motor noise, vibration or shudder under load
Rapid increase in inverter or motor temperature
Loss of regen or abnormal braking behavior
Possible high-voltage system warnings or interlock events

What to check

Read and record full DTC list and freeze-frame / stored data from hybrid/EV control module
Confirm vehicle is in a safe state and follow high-voltage isolation procedures before any physical inspection
Visually inspect inverter, motor and harness for damage, burns, melting, water intrusion, corrosion or loose connectors on Motor B phase V circuit
Check for related codes (other phase current faults, inverter temperature, DC bus faults)
Measure DC bus / HV battery voltage and compare with freeze-frame values
With HV isolated and discharged, measure resistance between phase terminals of Motor B (U-V-W) and compare — look for significantly lower resistance on V phase or short to chassis

Signal parameters

Phase currents (IA, IB, IC) — expected to be similar in magnitude with 120° phase shift; fault condition: phase V current significantly higher than other phases or above expected load
DC bus (HV) voltage — nominal battery pack voltage under the recorded condition
PWM gate-drive signals to phase V inverter leg — should match commanded duty; loss or abnormal switching may indicate power-stage failure
Motor speed (RPM) and torque command — used to compare expected current for given torque demand
Current sensor output voltage (or shunt voltage) for phase V — should scale linearly with current
Inverter temperature and motor temperature — elevated temps may correlate with failures

Diagnostic algorithm

Retrieve DTCs and freeze-frame data from the hybrid/EV control module; note vehicle conditions (speed, throttle, HV voltage) when fault set
Confirm safety: disable HV system, follow manufacturer procedures, wear PPE, and isolate HV before touching components
Perform a detailed visual inspection of inverter, motor, and phase V wiring/connectors for damage, corrosion, or water ingress
Check for other related codes (other phase faults, DC bus faults, inverter overtemp) to narrow cause
Measure DC bus voltage and verify it matches freeze-frame; verify HV interlocks are not tripping repeatedly
With HV safely isolated and discharged, measure phase-to-phase resistance on Motor B (compare U-V, V-W, W-U). A significantly lower resistance on the V leg or short to chassis suggests motor winding short or conductor short
Perform an insulation/continuity test from phase V conductor to chassis ground and to battery positive/negative to detect short circuits
Inspect and, if possible, test or replace the phase current sensor or shunt resistor and check associated wiring and connectors
Re-enable HV and capture live data with HV-capable current probes and oscilloscope/diagnostic tool: compare phase currents during a controlled run (low speed/low torque) — confirm whether current spike is present and whether PWM drive to phase V is normal
If the inverter gate signals are absent or irregular for phase V while other phases are normal, suspect inverter power stage failure; consult manufacturer service literature for inverter module bench test or replacement procedure
If motor winding tests indicate internal short, consider motor removal and bench evaluation or replacement
After repairs, clear codes and perform road-test with data logging to confirm normal phase currents and no recurrence of the DTC

Likely causes

Failed inverter power stage on Motor B (phase V transistor short)
Shorted or damaged phase V wiring/connector between inverter and motor
Faulty phase current sensor or related sensing circuitry
Motor winding short or internal motor failure

Fault status

⚠️ Status

Drive Motor B — Phase V current excessive. High phase current detected on Motor B (phase V). Service required; do not drive if vehicle is in limp or shutdown state. HV system precautions required.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 2.0-5.0 hours

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