Code
P0A20
Generic
P — Powertrain
Motor Torque Sensor Circuit High
Views:
UK: 15
EN: 15
RU: 12
AI status
Completed
Completed
100%
Causes
- Open, damaged, or chafed wiring in torque sensor signal or reference circuits
- Corroded, loose, or contaminated connector at sensor or inverter/ECU
- Failed torque sensor (internal short or internal amplifier fault)
- Faulty inverter/drive control module or ECU input stage
- Incorrect sensor reference voltage (overvoltage from supply)
- Short to battery voltage on the sensor signal or reference circuit
Symptoms
- Hybrid/EV system warning light or master warning illuminated
- Reduced power or limp mode / limited torque available
- Fault code P0A20 present in ECU/inverter memory
- Possible drivability issues when accelerating or poor torque response
- Intermittent faults if wiring is broken or corroded
What to check
- Read and record stored codes and freeze frame data with a capable scan tool; capture live data for torque sensor signal and related channels
- Verify vehicle is safely disabled for HV system work; follow manufacturer high‑voltage safety procedures before touching high‑voltage components
- Visually inspect wiring harness and connectors at torque sensor, motor/inverter and ECU for damage, corrosion, bent pins, water ingress, or signs of overheating
- Check connector seating and retention; unplug and inspect pins for contamination or corrosion
- Perform a wiggle test on harness while watching live data for changes or intermittent faults
- Verify low‑voltage power and ground supplies to the sensor (reference voltage) at the connector using a DMM
Signal parameters
- Typical torque sensor output: 0–5.0 V range (many designs use a 2.5 V center reference for bidirectional torque); expected idle/center ~2.5 V
- High fault threshold: sensor signal > ~4.5 V (varies by manufacturer) or above specified upper limit
- Low fault threshold: sensor signal < ~0.5 V or below specified lower limit
- Reference supply commonly 5 V ±0.25 V; check reference stability
- If a current‑based torque sensor is used, expect manufacturer specified mA or differential voltage; compare against service data
Diagnostic algorithm
- Safety first — disable high‑voltage system and follow lockout/tagout and insulated tool procedures before probing HV components
- Use a scan tool to confirm P0A20 and note freeze‑frame and related codes (e.g., torque sensor low/high, inverter faults). Clear codes and attempt to reproduce to confirm persistence
- Visually inspect connectors and harness from torque sensor to inverter/ECU. Repair any damage before further tests
- With vehicle safe and low voltage circuits accessible, backprobe the torque sensor connector and measure: reference voltage, signal voltage, and ground continuity. Compare to expected values in signal_params
- If signal is high at the sensor connector, disconnect sensor and measure with connector disconnected: if signal remains high, suspect short or ECU/inverter output stuck high; if signal drops to open circuit, suspect sensor internal fault
- Check continuity and resistance of signal and reference wires to the inverter/ECU; check for shorts to battery (+) and ground
- If wiring checks OK and signal still out of range, replace the torque sensor (or torque sensor module) per manufacturer procedure and retest
- If replacement sensor does not correct the fault, inspect/repair inverter/ECU input circuitry or replace inverter/ECU as directed by manufacturer diagnostics
- After repairs, clear codes, perform relearns/calibrations if required by service manual, and road test to confirm repair
Likely causes
- Damaged connector or wiring causing short to battery voltage
- Failed torque sensor (internal electronics)
- Faulty inverter/drive control module input or power supply
Fault status
Status
Stored when the motor torque sensor circuit voltage exceeds the allowed upper threshold. May be accompanied by reduced propulsion/inverter limp mode and related hybrid/EV system warnings. Freeze frame and live data available for diagnosis.
Repair difficulty: Hard
Diagnostic time: 2.0-4.0 hours
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