AutoCodes – Generic – U1138

U1138 Code - Invalid Or Missing Data For Primary Id

Quick Answer

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Common causes include Faulty Module that is not communicating, Module harness is open or shorted, 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: U1138 indicates Invalid Or Missing Data For Primary Id.
Common causes: Common causes include Faulty Module that is not communicating, Module harness is open or shorted, 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 8,820

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 Apr 23, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1138 Description

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for State of Health monitoring. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. When a module does not associate an identification number with at least one critical parameter within 5 seconds of beginning serial data communication, the Diagnostic Trouble Code (DTC) is set.

OBDII Code U1138 - Invalid Or Missing Data For Primary Id - AutoCodes.com — U1138 Code - Invalid Or Missing Data For Primary Id

What does this mean?

What are the Possible Causes of the DTC U1138?

Faulty Module that is not communicating
Module harness is open or shorted
Module circuit poor electrical connection

How to Fix the DTC U1138?

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 U1138 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 U1138 code?

Need more information on how to fix the U1138 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U1138 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 U1138 Code

1. What are the common symptoms of OBDII code U1138?

- Common symptoms include issues with the vehicle's transmission, engine misfires, rough idling, and poor fuel efficiency.

2. What can cause the OBDII code U1138 to trigger?

- This code is typically triggered by communication errors between the primary control module and other vehicle modules.

3. How do I diagnose the cause of the U1138 code?

- Diagnosing this code usually involves checking the wiring and connectors related to the primary control module, as well as testing the module itself for faults.

4. Can a faulty battery or alternator cause code U1138 to appear?

- Yes, a weak battery or failing alternator can sometimes lead to communication issues between vehicle modules and trigger the U1138 code.

5. Is it safe to continue driving with the U1138 code present?

- It is not recommended to drive with the U1138 code active, as it can lead to further damage to the vehicle's systems if left unresolved.

6. How can I clear the U1138 code from my vehicle's OBDII system?

- Clearing the U1138 code typically involves using an OBDII scanner to reset the system after identifying and fixing the underlying issue.

7. Are there any common repair tips for resolving the U1138 code?

- Common repair tips include checking and repairing any damaged wiring or connectors, ensuring proper grounding, and verifying the functionality of the primary control module.

8. Can extreme temperatures or weather conditions trigger code U1138?

- Yes, extreme temperatures or weather conditions can sometimes lead to temporary communication errors between vehicle modules and trigger the U1138 code.

9. How long does it usually take to repair the U1138 code issue?

- The repair time for the U1138 code can vary depending on the underlying cause, but it typically takes a few hours to diagnose and fix the problem.

10. Will the U1138 code cause my vehicle to fail an emissions test?

- Yes, the U1138 code can cause your vehicle to fail an emissions test, as it indicates a problem with the vehicle's emissions control system.

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