AutoCodesGMC – P0800 2018 GMC Sierra

P0800 2018 GMC Sierra Code - Active Transfer Case Control Module Requested MIL Illumination

Quick Answer

Control modules constantly monitor the vehicle for any condition which may adversely affect vehicle performance. Common causes include Check Active Transfer Case Control Module for codes, Faulty Active Transfer Case Control Module. 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
P0800 2018 GMC Sierra indicates Active Transfer Case Control Module Requested MIL Illumination.
Common causes
Common causes include Check Active Transfer Case Control Module for codes, Faulty Active Transfer Case Control Module.
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.
AI answers can be wrong. Verify repairs with testing. Open full chat
Code Popularity 211
How popular is this code, among other codes? Low
Table of contents Created and updated by William Orellana on Jul 15, 2022
💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0800 2018 GMC Sierra Description

Control modules constantly monitor the vehicle for any condition which may adversely affect vehicle performance. If a condition is detected, the module sets a Diagnostic Trouble Code (DTC) and sends a serial data message to the Engine Control Module (ECM). The ECM sets a DTC to inform that the module has set a DTC. The serial data message sent by the module also contains a request for the ECM to illuminate the Malfunction Indicator Lamp (MIL).
The DTC will be set when the ECM receives a serial data message from the Active Transfer Case Control Module indicating that DTC has been set in the module.
OBDII Code P0800 2018 GMC Sierra - Active Transfer Case Control Module Requested MIL Illumination - AutoCodes.com
P0800 2018 GMC Sierra Code - Active Transfer Case Control Module Requested MIL Illumination

What are the Possible Causes of the DTC P0800 2018 GMC Sierra?

  • Check Active Transfer Case Control Module for codes
  • Faulty Active Transfer Case Control Module

How to Fix the DTC P0800 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 P0800 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 P0800 2018 GMC Sierra code?

Need more information on how to fix the P0800 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0800 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 P0800 2018 GMC Sierra Code

1. What does the OBDII code P0800 mean on a 2018 GMC Sierra?

The P0800 code indicates that the Active Transfer Case Control Module has detected an issue and requested the Malfunction Indicator Lamp (MIL) to illuminate.

2. What are common symptoms of the P0800 code in a 2018 GMC Sierra?

Symptoms may include the check engine light illumination, drivetrain performance issues, difficulty switching between 2WD and 4WD modes, or unusual noises from the transfer case.

3. What causes the P0800 code to be triggered in a GMC Sierra?

Common causes include a faulty transfer case control module, wiring or connector issues, software glitches, or internal problems within the transfer case.

4. Is it safe to drive with the P0800 code active in my 2018 GMC Sierra?

Driving may be possible, but it’s not recommended as it could lead to further damage to the transfer case or drivetrain components.

5. How is the P0800 code diagnosed in a GMC Sierra?

A technician will use a scan tool to verify the code, inspect the transfer case control module, check for wiring or connector issues, and test the transfer case functionality.

6. Can the P0800 code be fixed by resetting the check engine light?

Simply resetting the light won’t fix the underlying issue. The root cause, such as module faults or wiring problems, must be addressed.

7. What repairs are typically needed to fix the P0800 code on a 2018 GMC Sierra?

Repairs may include replacing or reprogramming the transfer case control module, repairing damaged wiring, or addressing mechanical issues in the transfer case.

8. How much does it cost to fix the P0800 code in a GMC Sierra?

Repair costs vary but may range from $200 to $1,500, depending on whether the issue is electrical (module or wiring) or mechanical (transfer case components).

9. Can I fix the P0800 code on my GMC Sierra myself?

If you’re experienced with diagnostics and repairs, you can check the wiring, connectors, and module. Otherwise, it’s best to consult a professional.

10. What tools are needed to diagnose the P0800 code in a GMC Sierra?

You’ll need an OBDII scanner capable of reading manufacturer-specific codes, a multimeter for testing wiring, and possibly specialty tools for transfer case inspection.

Discuss the causes and fixes for P0800 2018 GMC Sierra OBDII Code

Code P0800 2018 GMC Sierra comments

No comments found for this page.

AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play