Home / DTC / P0A20 — Motor Torque Sensor Circuit High

P0A20 — Motor Torque Sensor Circuit High

Detailed page for trouble code P0A20.

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Code

P0A20

Generic P — Powertrain

Motor Torque Sensor Circuit High

Brand: Generic
Views: UK: 15 EN: 15 RU: 12
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Page language: EN

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

  1. Safety first — disable high‑voltage system and follow lockout/tagout and insulated tool procedures before probing HV components
  2. 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
  3. Visually inspect connectors and harness from torque sensor to inverter/ECU. Repair any damage before further tests
  4. 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
  5. 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
  6. Check continuity and resistance of signal and reference wires to the inverter/ECU; check for shorts to battery (+) and ground
  7. If wiring checks OK and signal still out of range, replace the torque sensor (or torque sensor module) per manufacturer procedure and retest
  8. If replacement sensor does not correct the fault, inspect/repair inverter/ECU input circuitry or replace inverter/ECU as directed by manufacturer diagnostics
  9. 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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