P0E91

Code

Generic P — Powertrain

Drive Motor B Inverter Voltage Sensor B” Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 21 EN: 31 RU: 26

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Page language: EN

Causes

Open or high-resistance wiring in voltage sensor B circuit
Short to ground or short to battery voltage in the sensor harness
Poor or corroded connector at the inverter or harness splice
Water ingress or physical damage to the inverter connector or harness
Failed inverter voltage sensor inside the inverter assembly
Faulty inverter control module (internal electronics)

Symptoms

MIL/EV system warning lamp or hybrid warning light illuminated
Reduced drive power or limited propulsion (limp/reduced-performance mode)
Loss of regenerative braking or reduced regen capability
Vehicle may not start in drive or will disable motor B
Stored related inverter/traction system codes and possible HV system interlocks

What to check

Review freeze frame and related DTCs with a compatible scan tool; record live data for inverter voltage sensor B
Follow manufacturer high-voltage safety procedure and isolate/de-energize HV system before any physical checks
Visually inspect wiring harness, connectors, and pin condition at Drive Motor B inverter and battery/inverter junctions for corrosion, damage or water ingress
Check connector mating and retention; look for bent/burnt pins
With HV system made safe, perform continuity and insulation resistance checks of the sensor wiring between the inverter connector and measurement points per service manual
Measure reference voltage and signal voltage at the inverter harness (after ensuring HV safety) using a low-voltage meter or scope where applicable

Signal parameters

Typical low-voltage sense reference: ~5 V supply to sensor circuit (verify factory spec)
Expected sensor output: proportional 0–5 V (approx. 0.0–4.9 V) corresponding to 0–battery pack max voltage (check vehicle-specific scale)
Open-circuit: no signal / voltage floats or reads out-of-range
Short-to-ground: ~0 V
Short-to-battery/reference: ~5 V constant
Resistance of wiring: near 0 ohms continuity between connector pins (verify per service limits)

Diagnostic algorithm

Ensure technician follows all manufacturer HV safety and isolation procedures before starting work
Retrieve and record all related DTCs and freeze-frame data with scan tool; note ignition state and vehicle conditions
With HV system made safe, visually inspect inverter B connectors, pigtails and harness for damage, corrosion, water entry, or overheating; repair as needed
Reconnect low-voltage diagnostic connectors and verify proper locking and pin seating
Back-probe the inverter voltage-sensor B terminals (or at service harness connector) with the HV system disabled/isolated as required to measure reference and signal circuits. Verify 5 V reference (or vehicle-specified reference) and that signal follows expected scaling when HV bus voltage is present (observe using safe powered checks as per manual)
Perform continuity and short-to-ground / short-to-B+ tests on the sensor signal circuit to locate open or short conditions (ensure high-voltage is isolated before insulation checks)
Use an oscilloscope or live-data capture to watch the sensor signal while performing wiggle tests and during controlled power-up to reproduce intermittent faults
If wiring and connectors pass, suspect internal inverter sensor failure; consult service info for inverter module replacement or internal repair procedures. Check for required reprogramming/calibration after replacement
After repairs, clear codes, re-enable HV system, and perform system self-check and road test to confirm the fault does not return

Likely causes

Corroded or loose inverter connector at Drive Motor B
Chafed wiring causing intermittent short to ground or +HV sense
Failed internal voltage-sensing component in the motor inverter
Water intrusion into harness/connector causing high resistance or short

Fault status

⚠️ Status

Drive Motor B Inverter Voltage Sensor B circuit fault — sensor reading out of range, open, or short. Inverter cannot reliably sense HV bus voltage for motor B.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5-3.0 hours