AutoCodes – Generic – U1029

U1029 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: U1029 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 5,992

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 U1029 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 U1029 - Invalid Or Missing Data For Primary Id - AutoCodes.com — U1029 Code - Invalid Or Missing Data For Primary Id

What does this mean?

What are the Possible Causes of the DTC U1029?

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

How to Fix the DTC U1029?

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 U1029 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 U1029 code?

Need more information on how to fix the U1029 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U1029 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 U1029 Code

1. What does the OBDII code U1029 mean?

U1029 indicates that the vehicle has detected invalid or missing data for the primary ID, typically involving communication issues between control modules.

2. What are the common symptoms of the U1029 code?

Symptoms may include a check engine light, communication errors with certain vehicle systems, improper functionality of electronic components, or a complete system failure.

3. What causes the U1029 code to appear?

Possible causes include faulty wiring, loose or corroded connectors, a malfunctioning control module, or issues with the CAN (Controller Area Network) bus communication.

4. Can the U1029 code cause the vehicle to stop functioning?

In some cases, the code can lead to the failure of critical systems, such as the engine, transmission, or powertrain components, depending on the affected module.

5. How can I diagnose the U1029 code?

Start by scanning the vehicle with an OBDII scanner, inspect the wiring and connectors for damage or corrosion, and test the affected control modules for proper communication.

6. Is it safe to drive with the U1029 code?

It depends on the severity of the issue. If essential systems like the engine or transmission are compromised, driving may not be safe. Have the vehicle inspected promptly.

7. What tools do I need to fix the U1029 code?

You'll need an OBDII scanner, a multimeter for testing electrical connections, and possibly a wiring diagram for your vehicle's communication system.

8. Can a software update fix the U1029 code?

In some cases, a software update for the affected control module can resolve the issue if itâ€™s caused by a programming or compatibility problem.

9. How much does it cost to repair the U1029 code?

Repair costs vary depending on the root cause. Simple wiring repairs may cost under $100, but replacing a faulty control module could cost several hundred dollars.

10. What should I do if the U1029 code reappears after repair?

If the code returns, recheck all wiring, connectors, and module communication. It may require professional diagnosis to identify hidden faults or intermittent issues.