AutoCodes – GMC – P0A40 GMC

P0A40 GMC 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 GMC 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 1,379

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
FAQs
Comments
Add Comment

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

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

What does this mean?

What are the Possible Causes of the DTC P0A40 GMC?

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 GMC?

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 GMC 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 GMC code?

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

Need Help with the Code?

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

Information for Specific GMC Models

P0A40 2016 GMC Sierra — Drive Motor Position Sensor Performance
P0A40 2017 GMC Sierra — Drive Motor Position Sensor Performance
P0A40 2018 GMC Sierra — Drive Motor Position Sensor 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.

Frequently Asked Questions about P0A40 GMC Code

1. What does the OBDII code P0A40 mean on a GMC vehicle?

P0A40 indicates an issue with the Drive Motor 1 Position Sensor, specifically a performance problem where the sensor is not providing accurate or expected readings.

2. What are the common symptoms of a P0A40 code in a GMC?

Symptoms may include reduced vehicle performance, an illuminated check engine light, difficulty accelerating, or unusual drivetrain behavior.

3. What causes the P0A40 code to appear in GMC vehicles?

The code can be triggered by a faulty Drive Motor 1 Position Sensor, damaged wiring or connectors, or issues with the hybrid drive motor's internal components.

4. Can I still drive my GMC with a P0A40 code?

Driving with a P0A40 code is not recommended, as it may lead to further damage to the hybrid system and reduced performance or safety.

5. How can I diagnose the P0A40 code?

Diagnosis involves scanning the vehicle with an OBDII scanner, inspecting the Drive Motor 1 Position Sensor, checking wiring and connectors for damage, and testing the hybrid motor system.

6. How do I fix a P0A40 code on my GMC?

Repairs may include replacing the Drive Motor 1 Position Sensor, repairing damaged wiring or connectors, or addressing internal hybrid motor issues if necessary.

7. How much does it cost to repair a P0A40 code on a GMC?

Repair costs vary but may range from $200 to $1,000, depending on whether the sensor, wiring, or hybrid motor requires attention.

8. Can a P0A40 code be caused by software issues?

While uncommon, a software issue or outdated ECM programming could contribute to the problem. Updating the ECM may resolve the code in some cases.

9. How can I prevent the P0A40 code from occurring again?

Regular maintenance, inspecting hybrid system components, and addressing electrical issues promptly can help prevent this code from recurring.

10. Can a P0A40 code trigger other issues in my GMC?

Yes, unresolved issues with the Drive Motor 1 Position Sensor can lead to additional drivetrain or hybrid system faults, potentially causing more significant problems over time.