Motor Torque Sensor Circuit Intermittent
The P0A21 code means the vehicle's onboard diagnostic system has detected: Motor Torque Sensor Circuit Intermittent. This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $150 - $900 (wiring at the low end; sensor access varies by model - diagnose before parts)
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Common Symptoms
- Check Engine Light on
- Hybrid system may limit torque or feel less responsive
- Torque value implausible or frozen on a scan tool
- Often no strong drivability symptom
Probable Causes (Ranked by Likelihood)
- Failed Motor Torque Sensor High
- Damaged wiring or corroded connector in the sensor circuit High
- Control-module input fault Moderate
Frequently Asked Questions
What does P0A21 mean?
P0A21 means the Motor Torque Sensor circuit is faulty - the module cannot trust the torque feedback it uses to blend engine and electric power.
Can I keep driving with P0A21?
Usually yes, with possibly reduced or less smooth power delivery. Diagnose soon; the system is running with degraded feedback.
Is P0A21 safe to work on myself?
This code involves the high-voltage system. Do not open the HV battery, inverter, or any orange-cabled component without hybrid-specific training, insulated gloves, and the service plug removed. Diagnosis beyond a scan-tool read belongs at a hybrid-qualified shop.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Read the code and live torque data with a hybrid-capable scan tool.
-
Compare commanded versus reported torque under gentle acceleration.
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Inspect the sensor wiring and connector before replacing parts.
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Follow the OEM pinpoint test for the Motor Torque Sensor.
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Commonly Affected Vehicles
- Toyota/Lexus hybrids (Prius, Camry Hybrid, RAV4 Hybrid)
- Ford/Lincoln hybrids (Escape, Fusion, C-MAX)
- Honda hybrids (Insight, Civic Hybrid, Accord Hybrid)
- Hyundai/Kia hybrids and plug-in hybrids
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