AutoCodes – Cadillac – P1649 Cadillac

P1649 Cadillac 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 Cadillac 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.

Save to My Repairs My Repairs

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

Code Popularity 538

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
Add Comment

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

Code P1649 Cadillac 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 Cadillac - Immobilizer Security Code Not Programmed - AutoCodes.com — P1649 Cadillac Code - Immobilizer Security Code Not Programmed

What does this mean?

What are the Possible Causes of the DTC P1649 Cadillac?

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 Cadillac?

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 Cadillac 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 Cadillac code?

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

Need Help with the Code?

Get the P1649 Cadillac 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 Cadillac Code

1. What does OBDII code P1649 for Cadillac mean?

OBDII code P1649 indicates that the immobilizer security code is not programmed in the vehicle's system, potentially leading to issues with starting the engine.

2. What are the common symptoms of OBDII code P1649 in a Cadillac?

Common symptoms include the engine not starting, the vehicle not recognizing the key, and the security light flashing on the dashboard.

3. What are the possible causes of OBDII code P1649 in a Cadillac?

Possible causes include a faulty immobilizer module, issues with the key or key fob, a problem with the key reader, or a communication error between components.

4. How can I diagnose OBDII code P1649 in my Cadillac?

Diagnosis usually involves using a scan tool to read the specific code, checking for any related trouble codes, and testing the key and immobilizer components for proper functionality.

5. Can I still drive my Cadillac with OBDII code P1649 present?

It's not recommended to drive the vehicle with this code present, as it can lead to starting issues and potential immobilization of the vehicle.

6. How can I repair OBDII code P1649 in my Cadillac?

Repairs may involve reprogramming the immobilizer system, replacing faulty components like the immobilizer module or key reader, or reprogramming new keys to the vehicle.

7. Can I reset OBDII code P1649 in my Cadillac myself?

In some cases, you may be able to reset the code by disconnecting the battery for a few minutes, but it's important to address the underlying issue to prevent the code from reappearing.

8. Is it safe to try DIY fixes for OBDII code P1649 in a Cadillac?

While some basic troubleshooting steps like checking key fob batteries can be done at home, more complex repairs involving the immobilizer system are best left to trained professionals.

9. How much does it cost to repair OBDII code P1649 in a Cadillac?

Repair costs can vary depending on the specific issue and the labor rates in your area, but it's advisable to get a diagnostic from a qualified mechanic to determine the exact repair needed.

10. How can I prevent OBDII code P1649 from occurring in my Cadillac again?

To prevent this code from recurring, ensure that keys are programmed correctly, avoid water damage to key components, and address any immobilizer system issues promptly.