AutoCodes – GMC – P1649 2018 GMC Sierra

P1649 2018 GMC Sierra Code - Immobilizer Security Code Not Programmed

Quick Answer

When learning the security code, as well as the challenge and response sequence, the Engine Control Module (ECM) is placed in learn mode. Common causes include Perform Engine Control Module Immobilizer Learn Procedure, Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted. 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: P1649 2018 GMC Sierra indicates Immobilizer Security Code Not Programmed.
Common causes: Common causes include Perform Engine Control Module Immobilizer Learn Procedure, Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted.
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 161

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 17, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1649 2018 GMC Sierra Description

When learning the security code, as well as the challenge and response sequence, the Engine Control Module (ECM) is placed in learn mode. Once the security code and challenge/response are learned, learn mode will be exited when the engine is successfully started. The Diagnostic Trouble Code (DTC) will be set when the ECM has not learned a security code.

OBDII Code P1649 2018 GMC Sierra - Immobilizer Security Code Not Programmed - AutoCodes.com — P1649 2018 GMC Sierra Code - Immobilizer Security Code Not Programmed

What does this mean?

What are the Possible Causes of the DTC P1649 2018 GMC Sierra?

Perform Engine Control Module Immobilizer Learn Procedure
Faulty Engine Control Module (ECM)
Engine Control Module harness is open or shorted
Engine Control Module circuit poor electrical connection

How to Fix the DTC P1649 2018 GMC Sierra?

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 P1649 2018 GMC Sierra 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 P1649 2018 GMC Sierra code?

Need more information on how to fix the P1649 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1649 2018 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 P1649 2018 GMC Sierra Code

1. What are the common symptoms of OBDII code P1649 "Immobilizer Security Code Not Programmed" in a 2018 GMC Sierra?

When this code is present, you may experience issues starting the vehicle, the engine may not turn over, and the security light may illuminate on the dashboard.

2. What causes the OBDII code P1649 to appear in a 2018 GMC Sierra?

The primary cause of this code is a communication error between the vehicle's immobilizer system and the engine control module (ECM).

3. How can I diagnose the OBDII code P1649 in my 2018 GMC Sierra?

A diagnostic scan tool can be used to retrieve the specific trouble codes, followed by checking the wiring connections between the immobilizer system and the ECM.

4. Can I drive my 2018 GMC Sierra with the OBDII code P1649?

It is not recommended to drive the vehicle with this code active, as it may result in starting issues or potential security concerns due to the immobilizer system not being programmed.

5. How can I repair the OBDII code P1649 in my 2018 GMC Sierra?

To resolve this issue, the immobilizer system may need to be reprogrammed or reset by a professional mechanic with access to the necessary tools and software.

6. Is it possible to reset the immobilizer system in a 2018 GMC Sierra without professional help?

Resetting the immobilizer system typically requires specialized equipment and knowledge, so it is best to consult a trained technician for proper diagnosis and repair.

7. Are there any temporary fixes for the OBDII code P1649 in a 2018 GMC Sierra?

While temporary fixes may not be recommended, some users have reported success by disconnecting the battery for a few minutes to reset the system. However, this may not resolve the underlying issue.

8. Will the OBDII code P1649 in a 2018 GMC Sierra cause any long-term damage if left unresolved?

Leaving this code unresolved may lead to persistent starting issues, potential security risks, and could eventually cause further damage to the vehicle's electronic systems if not addressed promptly.

9. How much does it typically cost to repair the OBDII code P1649 in a 2018 GMC Sierra?

The cost of repairing this code can vary depending on the extent of the issue and the labor rates in your area. It is advisable to obtain quotes from reputable mechanics or dealerships for an accurate estimate.

10. Can a software update or reflash fix the OBDII code P1649 in a 2018 GMC Sierra?

In some cases, a software update or reflash of the ECM and immobilizer system may resolve the communication error causing this code. It is best to consult a professional technician for proper diagnosis and repair recommendations.