AutoCodes – Generic – U0138

U0138 Code - Lost Communication With All Terrain Control Module

Quick Answer

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Common causes include Faulty All-Terrain Control Module, All-Terrain Control Module harness is open or shorted, All-Terrain Control Module circuit poor electrical connection. 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: U0138 indicates Lost Communication With All Terrain Control Module.
Common causes: Common causes include Faulty All-Terrain Control Module, All-Terrain Control Module harness is open or shorted, All-Terrain Control Module circuit poor electrical connection.
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 11,477

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 Mar 31, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0138 Description

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Operating information and commands are exchanged among the devices. The devices have programmed information about what messages are needed to be exchanged on the serial data circuits. CAN bus uses two dedicated wires for communication. The wires are called CAN high and CAN low. When the CAN bus is in idle mode, both lines carry 2.5V. When data bits are being transmitted, the CAN high line goes to 3.75V, and the CAN low drops to 1.25V, thereby generating a 2.5V differential between the lines. Since communication relies on a voltage differential between the two bus lines, the CAN bus is NOT sensitive to inductive spikes, electrical fields, or other noise. The Diagnostic Trouble Code (DTC) sets when a periodic message from the All-Terrain Control Module has not been received.

OBDII Code U0138 - Lost Communication With All Terrain Control Module - AutoCodes.com — U0138 Code - Lost Communication With All Terrain Control Module

What does this mean?

What are the Possible Causes of the DTC U0138?

Faulty All-Terrain Control Module
All-Terrain Control Module harness is open or shorted
All-Terrain Control Module circuit poor electrical connection

How to Fix the DTC U0138?

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 U0138 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 U0138 code?

Need more information on how to fix the U0138 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U0138 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U0138 Ford — Lost Communication With All Terrain Control Module
U0138 Lincoln — Lost Communication With All Terrain Control Module
U0138 Mercury — Lost Communication With All Terrain Control Module

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 U0138 Code

1. What are common symptoms of OBDII code U0138 (Lost Communication With All Terrain Control Module)?

- Common symptoms include the illumination of the Check Engine Light, traction control system malfunction, ABS system issues, and potentially rough shifting in automatic transmissions.

2. What are some possible causes of OBDII code U0138?

- Possible causes include a faulty All Terrain Control Module (ATCM), damaged wiring or connectors related to the ATCM, a blown fuse, software issues, or a communication bus fault.

3. How can I diagnose the cause of OBDII code U0138?

- To diagnose the cause, you can start by checking the wiring and connectors related to the ATCM for any visible damage. Using a scan tool to access the ATCM module for trouble codes and data can also help pinpoint the issue.

4. How can I repair OBDII code U0138?

- Repairing this code typically involves addressing the underlying cause, such as replacing a faulty ATCM, repairing damaged wiring or connectors, checking and replacing fuses as needed, or updating software if necessary.

5. Can I continue driving with OBDII code U0138 present?

- It is not recommended to continue driving with this code present, as it can lead to further issues with the traction control and ABS systems, affecting the vehicle's safety and performance.

6. Is it possible to reset OBDII code U0138 without fixing the underlying issue?

- While you can clear the code with a scan tool, it is important to address the underlying problem causing the communication loss to prevent the code from reoccurring and ensure proper functioning of the ATCM.

7. How do I prevent OBDII code U0138 from coming back?

- Regular maintenance checks, addressing any wiring or connector issues promptly, ensuring proper software updates for the ATCM, and following manufacturer recommendations can help prevent the recurrence of this code.

8. Can a DIY enthusiast repair OBDII code U0138, or is it best left to professionals?

- Depending on your skill level and access to tools, DIY enthusiasts may be able to address this code by following diagnostic procedures and repair steps outlined in the vehicle's service manual. However, complex wiring or module replacement may require professional assistance.

9. How long does it typically take to repair OBDII code U0138?

- The repair time can vary based on the underlying cause and the complexity of the repair needed. Simple fixes like replacing a fuse or clearing a communication fault may take a short time, while diagnosing and replacing a faulty ATCM could take longer.

10. Does OBDII code U0138 affect vehicle performance?

- Yes, this code can affect vehicle performance by causing issues with the traction control system, ABS system, and potentially impacting overall drivability and safety. Addressing the code promptly is crucial to maintaining optimal performance.