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DTC codes / P0Axx · Hybrid propulsion / P0A45

P0A45Drive Motor B Position Sensor Circuit

P0A45 indicates that the hybrid or electric vehicle control module has detected a fault in the position sensor circuit for drive motor B, which is the electric motor that typically provides propulsion or regenerative braking. The computer monitors the sensor's signal voltage and flags the code when the reading falls outside the expected range or is inconsistent with other motor data, meaning it cannot reliably determine the motor's rotor position.

SystemPowertrain
Code typeGeneric (all makes)
SeverityHigh
Fix difficultyProfessional
AreaHybrid propulsion

Symptoms you may notice

  • Illumination of the check engine light or hybrid system warning light, often with no other noticeable symptoms
  • Reduced power or a limp-home mode that limits vehicle speed
  • The engine may fail to start or the vehicle may not move when in gear
  • Rough operation or shuddering during acceleration or regenerative braking
  • A message on the dashboard indicating a hybrid system fault or service required

Common causes, most likely first

  1. A faulty position sensor (resolver) internal to drive motor B
  2. Damaged, chafed, or corroded wiring in the sensor circuit harness
  3. Loose or corroded electrical connectors at the motor or control module
  4. A failed motor control module or inverter assembly
  5. Mechanical damage to the motor's resolver rotor or stator
  6. Water intrusion or contamination in the motor housing or connector

How to diagnose and fix it

  1. Perform a visual inspection of the motor B position sensor wiring and connectors for damage or corrosion
  2. Check for technical service bulletins (TSBs) or software updates for the hybrid control module that may address false settings
  3. Measure the resistance and signal output of the position sensor with a multimeter and compare to manufacturer specifications
  4. Back-probe the sensor circuit at the control module to verify signal integrity and check for shorts or opens
  5. If the sensor is faulty, replace the drive motor B position sensor or the entire motor assembly as required
  6. After repair, clear the diagnostic trouble codes and perform a road test to verify the fix and ensure the code does not return

Common Misdiagnosis Traps for P0A45

  • A weak or failing 12-volt auxiliary battery can cause erratic sensor signals and set this code, so always load-test the battery before condemning the motor sensor.
  • The position sensor circuit often shares a ground with other sensors; a bad ground can trigger P0A45 along with other codes, so check ground integrity first.
  • Some aftermarket scan tools misreport resolver faults as position sensor codes; use a factory-level scan tool to view live motor position data and confirm the fault.
  • A damaged resolver rotor can mimic a sensor failure, so inspect the rotor for debris or mechanical damage if the sensor itself tests good.
  • This code can be set by a momentary loss of communication during a low-voltage event, so check for history codes and freeze-frame data before replacing parts.

Can I keep driving with P0A45?

Do not continue driving with this code active, as the vehicle may enter a reduced-power mode or fail to move, increasing the risk of an accident. Have the vehicle towed to a qualified repair facility for diagnosis.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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