Powertrain, generic · Hybrid propulsion

P0A19 Motor Torque Sensor Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The control unit watches the voltage of a torque sensor that measures load directly on the traction motor shaft, such as the magnetostrictive sensor in a hollow motor shaft shown in a Honda patent. P0A19 sets when the signal stays below its valid window for a calibrated time, typical of a short to ground, a broken supply or an open signal line pulled low. No manufacturer documents P0A19 publicly; CARB only requires an approved drive motor monitoring plan. P0A20 is the opposite fault, P0A18 a plausible voltage with wrong torque, P0A21 dropouts. The driver usually sees a hybrid warning and reduced electric drive power.

Likely causes

Sensor signal or supply line shorted to ground
Sensor reference or excitation supply missing
Corroded or loose connector at the drive unit
Torque sensor electronics failed, often replaced with the drive unit

Symptoms

  • Hybrid system warning light
  • Reduced electric drive power or electric drive disabled
  • Engine runs more often, higher fuel consumption

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–3,000
Time1–8 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

motor torque sensorwiring harnesshybrid control module

Related codes

P0A17P0A18P0A20P0A21

References: patents.google.com, law.cornell.edu.