AutoCodes – GMC – P0633 GMC

P0633 GMC Code - Immobilizer Key Not Programmed

Quick Answer

When learning the immobilizer data, as well as the challenge and response sequence, the Engine Control Module (ECM) is placed in learn mode. Common causes include Immobilizer Key not programmed to the vehicle, Faulty Immobilizer Key, Faulty ignition switch. 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: P0633 GMC indicates Immobilizer Key Not Programmed.
Common causes: Common causes include Immobilizer Key not programmed to the vehicle, Faulty Immobilizer Key, Faulty ignition switch.
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 8,183

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Jul 17, 2022

Description
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code P0633 GMC Description

When learning the immobilizer data, as well as the challenge and response sequence, the Engine Control Module (ECM) is placed in learn mode. The Diagnostic Trouble Code (DTC) P0633 will be set automatically as an indicator that the system is in learn mode and not as a fault indicator. Once the immobilizer data and challenge/response are learned, learn mode will be exited when the engine is successfully started. If the ECM does not exit learn mode, the DTC P0633 will remain current and indicate a fault.

OBDII Code P0633 GMC - Immobilizer Key Not Programmed - AutoCodes.com — P0633 GMC Code - Immobilizer Key Not Programmed

What does this mean?

What are the Possible Causes of the DTC P0633 GMC?

Immobilizer Key not programmed to the vehicle
Faulty Immobilizer Key
Faulty ignition switch

How to Fix the DTC P0633 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 does this mean?

Code Tech Notes

DTC P0633 will clear upon a successful engine start. Any malfunction that will cause a no-start condition will prevent DTC P0633 from clearing. Prior to diagnosing DTC P0633, ensure that all power moving, and engine control systems are operating properly and all conditions that may cause a no-start have been corrected. Do not replace the Engine Control Module (ECM). Replacing the Engine Control Module will not correct the no-start condition.

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0633 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.

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Information for Specific GMC Models

P0633 2014 GMC Sierra — Immobilizer Key Not Programmed
P0633 2015 GMC Sierra — Immobilizer Key Not Programmed
P0633 2016 GMC Sierra — Immobilizer Key Not Programmed
P0633 2017 GMC Sierra — Immobilizer Key Not Programmed
P0633 2018 GMC Sierra — Immobilizer Key Not Programmed

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 P0633 GMC Code

1. What does the OBDII code P0633 mean on a GMC vehicle?

P0633 indicates that the immobilizer key is not programmed to the vehicle’s engine control module (ECM) or body control module (BCM), preventing the vehicle from starting.

2. What are the common symptoms of a P0633 code?

The most common symptoms include the engine failing to start, the immobilizer warning light illuminating, and possible security system errors displayed on the dashboard.

3. What causes the P0633 code to appear?

The code is typically caused by an unprogrammed or incorrectly programmed key, a faulty immobilizer system, or a problem with the ECM/BCM communication.

4. Can a dead key fob battery trigger the P0633 code?

A dead key fob battery itself won’t trigger the code, but if the key cannot communicate with the immobilizer due to the low battery, it may simulate similar symptoms.

5. How do I fix the P0633 code on a GMC vehicle?

The key must be reprogrammed using a compatible diagnostic scanner or by taking the vehicle to a dealership or locksmith with the proper equipment.

6. Can I reprogram the immobilizer key myself to clear the P0633 code?

Reprogramming often requires specialized tools and knowledge. While some vehicles allow DIY reprogramming, most GMC models require a dealership or professional locksmith.

7. Is the P0633 code serious?

Yes, it is serious as it prevents the vehicle from starting, leaving you stranded unless resolved.

8. Can a P0633 code be caused by a faulty ECM or BCM?

Yes, a malfunctioning ECM or BCM can fail to recognize the key, triggering the P0633 code.

9. How much does it cost to fix a P0633 code on a GMC?

The cost varies but generally ranges from $100 to $300 for key reprogramming or immobilizer repairs. Additional costs may apply if the ECM or BCM is faulty.

10. Will disconnecting the battery clear the P0633 code?

No, disconnecting the battery will not resolve the issue, as the code relates to key programming and requires reprogramming or repair of the immobilizer system.