P0D31

Code

Generic P — Powertrain

Drive Motor A Inverter Voltage Sensor A” Circuit Intermittent/Erratic

Brand: Generic

Type: P — Powertrain

Views: UK: 20 EN: 37 RU: 23

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Causes

Loose, corroded or damaged wiring/connector on inverter voltage-sense circuit
High-resistance or intermittent connection at a terminal or ground
Water/moisture intrusion or contamination at connector or inverter
Internal failure of the inverter’s voltage sense circuitry or voltage divider
Intermittent short to battery positive or ground, or HV wiring damage
Inverter control module firmware or calibration anomaly

Symptoms

Malfunction Indicator Lamp (MIL) or hybrid/electric system warning illuminated
Reduced propulsion power or vehicle entered limp/limited-power mode
Loss or reduction of regenerative braking
Erratic torque or sudden torque cuts during acceleration
Inverter or HV system fault messages displayed to driver
Intermittent faults that may clear temporarily after restart

What to check

Record freeze frame and DTC history; check for related HV/inverter codes
Perform visual inspection of inverter and harness for damage, corrosion, contamination, or loose connectors
Confirm vehicle in a safe state and follow manufacturer high-voltage isolation procedures before touching components
Check low-voltage power and grounds for inverter control module
Scan live data to observe voltage-sensor signal behavior while cranking/at idle and under load
Wiggle test harness/connectors (monitor live data) to try to reproduce intermittent behavior

Signal parameters

Voltage-sense output typically a low-voltage signal derived from DC link (scaled to ~0–5.0 V) — exact scale is manufacturer-specific
Expected steady value should correlate with DC link/high-voltage bus; sudden spikes/drops or noise indicate intermittent/high-resistance connection
If available, scope waveform should be stable DC with low noise; intermittent jumps or ringing indicate wiring or sensor issues
CAN/inverter status messages may include DC link voltage and fault flags — compare sensed value to commanded/calculated value

Diagnostic algorithm

Safety first: follow manufacturer procedures to disable high-voltage system and wear appropriate PPE before inspecting HV components.
Read and record all stored DTCs, freeze frame and live data. Note if other inverter or HV codes are present.
Visually inspect inverter connectors, harness routing, and strain reliefs for damage, corrosion, contamination, or water entry. Repair any obvious damage.
With vehicle safely made safe for measurement (per manufacturer), reconnect low-voltage and perform live-data monitoring of the voltage-sense channel while an assistant cycles the vehicle through states (key on, ready, drive) and while applying load. Look for intermittent or erratic values.
Perform a wiggle test on the harness and connectors while watching the live sensor value; isolate the region where the value changes.
Measure pin-to-pin continuity and resistance of the voltage-sense circuit from the inverter connector to the sensor input/ground. Check for high resistance, opens, or shorts to chassis/HV.
Use an oscilloscope to observe the sensor signal during normal operation if available — intermittent spikes/noise indicate wiring or sensor conditioning issues.
Check inverter low-voltage power and ground integrity; high-resistance ground can cause erratic sensor readings.
If wiring and connectors test good, suspect internal inverter voltage-sense circuitry. Before replacing the inverter, check for available software updates or Technical Service Bulletins.
After repair, clear DTCs, perform functional/road test and re-scan to confirm fault does not return. If intermittent issues persist, further module bench testing or module replacement may be required.

Likely causes

Damaged insulation or chafed conductor on the voltage-sense harness causing intermittent contact
Corroded pin or connector causing high resistance and fluctuating voltage readings
Faulty resistor-divider or signal-conditioning circuit inside the inverter
Loose mounting or poor ground at inverter HV/low-voltage chassis ground
Contamination (moisture/salt) at the sensor connector causing intermittent continuity