AutoCodes – Generic – U1103

U1103 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: U1103 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 21,533

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 U1103 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 U1103 - Invalid Or Missing Data For Primary Id - AutoCodes.com — U1103 Code - Invalid Or Missing Data For Primary Id

What does this mean?

What are the Possible Causes of the DTC U1103?

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

How to Fix the DTC U1103?

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 U1103 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 U1103 code?

Need more information on how to fix the U1103 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U1103 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 U1103 Code

1. What does the OBDII code U1103 mean?

Code U1103 indicates "Invalid or Missing Data for Primary ID," which typically occurs when there is a communication issue between modules in the vehicle's network.

2. What are common symptoms of code U1103?

Symptoms may include the check engine light turning on, erratic behavior of vehicle systems like the instrument cluster, or loss of functionality in certain modules.

3. What causes the U1103 code?

Common causes include faulty wiring or connectors in the communication network, damaged control modules, or software issues in one of the vehicle's electronic systems.

4. Can a weak battery cause code U1103?

Yes, a weak or failing battery can result in voltage drops that disrupt communication between modules, potentially triggering the U1103 code.

5. How can I diagnose code U1103?

Start by inspecting the wiring and connectors associated with the vehicle's communication network. Use a diagnostic scanner to check for related codes and identify which module is failing to communicate.

6. Is code U1103 serious?

While it may not directly affect drivability, U1103 can disrupt communication between critical systems, leading to potential safety or performance issues if not addressed.

7. How do I fix code U1103?

Repair or replace any damaged wiring or connectors, check the battery and charging system, and update or reprogram the affected control module if necessary.

8. Can I clear code U1103 without fixing the issue?

Clearing the code without addressing the root cause may temporarily turn off the check engine light, but the code will likely reappear as the underlying issue persists.

9. Does code U1103 only affect certain vehicle makes and models?

No, U1103 can appear in any vehicle equipped with an OBDII system, but the exact systems affected may vary depending on the manufacturer.

10. Can U1103 be caused by a software glitch?

Yes, outdated or corrupted software in one of the control modules can lead to invalid or missing data, triggering the U1103 code.

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