AutoCodes – Generic – U1187

U1187 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: U1187 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 8,577

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 26, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1187 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 U1187 - Invalid Or Missing Data For Primary Id - AutoCodes.com — U1187 Code - Invalid Or Missing Data For Primary Id

What does this mean?

What are the Possible Causes of the DTC U1187?

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

How to Fix the DTC U1187?

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 U1187 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.

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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 U1187 Code

1. What does OBDII code U1187 mean?

Code U1187 indicates "Invalid Or Missing Data For Primary ID," which signifies a communication issue between modules in the vehicle's network.

2. What are common symptoms of code U1187?

Typical symptoms include warning lights on the dashboard, erratic or malfunctioning vehicle systems, and possible loss of functionality in features like ABS or traction control.

3. What causes code U1187?

U1187 can be caused by wiring issues, faulty connectors, damaged control modules, or software glitches affecting communication between modules.

4. Can driving with code U1187 damage my vehicle?

While it may not directly damage the vehicle, unresolved communication issues can lead to malfunctions in critical systems like braking or stability control.

5. How do you diagnose code U1187?

Diagnosis involves using an advanced scan tool to check the communication network, inspecting wiring and connectors, and verifying the integrity of affected control modules.

6. Can a weak battery cause code U1187?

Yes, a weak or failing battery can disrupt module communication and trigger U1187, as electrical systems rely on consistent voltage.

7. How do you fix code U1187?

Repairs may include replacing damaged wiring, repairing connectors, updating module software, or replacing a faulty control module.

8. Is code U1187 specific to certain vehicle makes?

No, U1187 is a generic communication-related code found across many vehicle makes and models equipped with OBDII systems.

9. What tools are needed to address code U1187?

A professional-grade scan tool with network diagnostics, multimeter, and wiring diagrams are essential for diagnosing and repairing U1187.

10. How much does it cost to repair code U1187?

Repair costs vary widely depending on the specific cause but can range from $100 for simple wiring fixes to over $1,000 for module replacement or software updates.