AutoCodes – Generic – P0A4A

P0A4A Code - Drive Motor 'B' Position Sensor Circuit Overspeed

Quick Answer

A resolver is a sensor that is used to detect the position of the magnetic poles the rotor of a motor generator. Common causes include Faulty Inverter with converter assembly, Faulty Hybrid vehicle generator assembly, Faulty Hybrid vehicle motor assembly. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0A4A indicates Drive Motor 'B' Position Sensor Circuit Overspeed.
Common causes: Common causes include Faulty Inverter with converter assembly, Faulty Hybrid vehicle generator assembly, Faulty Hybrid vehicle motor assembly.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 16,686

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on May 11, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P0A4A Description

A resolver is a sensor that is used to detect the position of the magnetic poles the rotor of a motor generator. Knowing the position of the poles is indispensable for ensuring precise control of MG2 and MG1.
Each resolver contains a stator that has an excitation coil and 2 detection coils (S, C). The gap between the stator and rotor changes as the rotor turns because the rotor is oval shaped. An alternating current with a predetermined frequency flows through the excitation coil, and detection coils S and C output alternating currents in accordance with the sensor rotor position.
The inverter with converter assembly (MG ECU) detects the absolute position of the rotor according to the phases of detection coils S and C and the heights of their waveforms. Furthermore, the CPU calculates the amount of change in the position within a predetermined length of time, in order to use the resolver as a speed sensor.
The MG ECU monitors signals output from the motor resolver and detects malfunctions.

OBDII Code P0A4A - Drive Motor 'B' Position Sensor Circuit Overspeed - AutoCodes.com — P0A4A Code - Drive Motor 'B' Position Sensor Circuit Overspeed

What does this mean?

What are the Possible Causes of the DTC P0A4A?

Faulty Inverter with converter assembly
Faulty Hybrid vehicle generator assembly
Faulty Hybrid vehicle motor assembly
Wire harness or connector

How to Fix the DTC P0A4A?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0A4A code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.