AutoCodes – Generic – P0A40

P0A40 Code - Drive Motor 1 Position Sensor Performance

Quick Answer

The drive motor position sensor is monitored by the motor control module. Common causes include Faulty Drive Motor 1 Position Sensor, Drive Motor 1 Position Sensor harness is open or shorted, Drive Motor 1 Position Sensor circuit poor electrical connection. 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: P0A40 indicates Drive Motor 1 Position Sensor Performance.
Common causes: Common causes include Faulty Drive Motor 1 Position Sensor, Drive Motor 1 Position Sensor harness is open or shorted, Drive Motor 1 Position Sensor circuit poor electrical connection.
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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 13,752

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 Aug 06, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0A40 Description

The drive motor position sensor is monitored by the motor control module. The motor control module monitors the angular position, speed, and direction of the drive motor rotor based upon the signals of the resolver-type position sensor. The position sensor contains a drive coil, two driven coils, and an irregular-shaped metallic rotor. The metallic rotor is mechanically attached to the shaft of the drive motor. At vehicle ON, the motor control module outputs a 7 V AC, 10 kHz excitation signal to the drive coil. The drive coil excitation signal creates a magnetic field surrounding the two driven coils and the irregular-shaped rotor. The motor control module then monitors the two driven coil circuits for return signals, often referred to as Sine and Cosine waveforms, abbreviated SIN and COS. The position of the irregular metallic rotor causes the magnetically induced return signals of the driven coils to vary in size and shape. A comparison of the two driven coil signals allows the motor control module to determine the exact position, speed, and direction of the drive motor rotor. The drive motor 1 position sensor is serviceable separately from the drive motor assembly. The Diagnostic Trouble Code (DTC) will be set when the motor control module detects a degraded motor position sensor signal.

OBDII Code P0A40 - Drive Motor 1 Position Sensor Performance - AutoCodes.com — P0A40 Code - Drive Motor 1 Position Sensor Performance

What does this mean?

What are the Possible Causes of the DTC P0A40?

Faulty Drive Motor 1 Position Sensor
Drive Motor 1 Position Sensor harness is open or shorted
Drive Motor 1 Position Sensor circuit poor electrical connection
Faulty Power Inverter Module

How to Fix the DTC P0A40?

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 P0A40 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.

Need more information about the P0A40 code?

Need more information on how to fix the P0A40 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0A40 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P0A40 Buick — Drive Motor 1 Position Sensor Performance
P0A40 Cadillac — Drive Motor 1 Position Sensor Performance
P0A40 Chevrolet — Drive Motor 1 Position Sensor Performance
P0A40 GMC — Drive Motor 1 Position Sensor Performance
P0A40 Lexus — Drive Motor 'A' Position Sensor Circuit Range/Performance
P0A40 Saturn — Drive Motor 1 Position Sensor Performance
P0A40 Toyota — Drive Motor 'A' Position Sensor Circuit Range/Performance

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.