AutoCodes – Generic – P0800

P0800 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 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.

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Code Popularity 2,622

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 Jul 15, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0800 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 - Active Transfer Case Control Module Requested MIL Illumination - AutoCodes.com — P0800 Code - Active Transfer Case Control Module Requested MIL Illumination

What does this mean?

What are the Possible Causes of the DTC P0800?

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

How to Fix the DTC P0800?

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 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 code?

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

Need Help with the Code?

Get the P0800 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P0800 Buick — Active Transfer Case Control Module Requested MIL Illumination
P0800 Cadillac — Active Transfer Case Control Module Requested MIL Illumination
P0800 Chevrolet — Active Transfer Case Control Module Requested MIL Illumination
P0800 GMC — Active Transfer Case Control Module Requested MIL Illumination

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 Code

1. What are the common symptoms of OBDII code P0800?

The common symptoms of OBDII code P0800 include the Check Engine Light (MIL) coming on, difficulty shifting gears, and issues with the transfer case control module.

2. What does the OBDII code P0800 indicate?

OBDII code P0800 indicates that the Active Transfer Case Control Module has requested the Malfunction Indicator Lamp (MIL) to illuminate, signaling a problem with the transfer case control system.

3. What are the possible causes of OBDII code P0800?

Possible causes of OBDII code P0800 include a faulty transfer case control module, wiring issues, a malfunctioning transfer case motor, or a problem with the vehicle's computer system.

4. How can I diagnose OBDII code P0800?

Diagnosing OBDII code P0800 involves using a diagnostic scanner to retrieve the code, checking the transfer case control module and motor for faults, and inspecting the wiring for any damage or loose connections.

5. Can I continue driving with OBDII code P0800 present?

It is not recommended to continue driving with OBDII code P0800 present, as it may lead to further damage to the transfer case system and potentially affect the vehicle's drivability.

6. How can I repair OBDII code P0800?

Repairing OBDII code P0800 typically involves replacing the faulty transfer case control module, repairing any damaged wiring, or addressing any issues with the transfer case motor as needed.

7. Is it possible to reset OBDII code P0800 without repairs?

Resetting OBDII code P0800 without addressing the underlying issue is not recommended, as the code is likely to reappear once the problem persists.

8. Can a DIY enthusiast fix OBDII code P0800?

Depending on the DIY enthusiast's skill level and access to tools, it may be possible to address OBDII code P0800 by replacing the transfer case control module or checking and repairing any wiring issues.

9. Will OBDII code P0800 affect fuel efficiency?

OBDII code P0800 may indirectly affect fuel efficiency if the transfer case control module issue leads to drivability problems that impact the vehicle's overall performance.

10. How much does it cost to repair OBDII code P0800?

The cost to repair OBDII code P0800 can vary depending on the underlying cause, parts needed for replacement, and labor charges. It is advisable to consult a professional mechanic for an accurate estimate.