AutoCodes – Generic – U1125

U1125 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: U1125 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 5,575

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 22, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1125 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 U1125 - Invalid Or Missing Data For Primary Id - AutoCodes.com — U1125 Code - Invalid Or Missing Data For Primary Id

What does this mean?

What are the Possible Causes of the DTC U1125?

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

How to Fix the DTC U1125?

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 U1125 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 U1125 code?

Need more information on how to fix the U1125 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U1125 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 U1125 Code

1. What does the OBDII code U1125 mean?

The U1125 code indicates that the vehicle's communication system has detected invalid or missing data for the primary identification module, often related to the CAN (Controller Area Network) bus.

2. What are the common symptoms of the U1125 code?

Symptoms may include warning lights on the dashboard (like the check engine light), erratic vehicle behavior, loss of communication with certain modules, or issues with starting the vehicle.

3. What causes the U1125 code to appear?

The code can be triggered by faulty wiring, a malfunctioning control module, damaged connectors, or software issues in the vehicle's communication system.

4. Can a weak battery cause the U1125 code?

Yes, a weak or failing battery can disrupt communication between modules, potentially causing the U1125 code to appear.

5. How do I diagnose the U1125 code?

Diagnosing this code typically involves checking for other codes, inspecting the wiring and connectors, testing module communication, and verifying the integrity of the CAN bus system.

6. Can the U1125 code cause drivability issues?

Yes, depending on the module affected, it can lead to performance problems, starting issues, or loss of critical vehicle functions.

7. How do I fix the U1125 code?

Repairs may involve addressing wiring or connector issues, replacing a faulty control module, or updating the software for the affected system.

8. Is the U1125 code specific to certain car brands?

No, the U1125 code is a generic communication-related code and can appear on various makes and models, though specific diagnostics may vary.

9. Can I drive with the U1125 code active?

It’s not recommended to drive with this code active, as it could lead to further damage or safety issues if critical systems are affected.

10. Do I need a professional to fix the U1125 code?

While some basic checks like inspecting wiring can be done at home, diagnosing and repairing communication faults often require specialized tools and expertise, so professional assistance is recommended.