P0A20

Code

Generic P — Powertrain

Motor Torque Sensor Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 20 EN: 27 RU: 21

AI status

Completed

ready

Completed 100%

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

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