AutoCodes – Generic – U1199

U1199 Code - Invalid Or Missing Data For External Access

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: U1199 indicates Invalid Or Missing Data For External Access.
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 8,324

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 U1199 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 U1199 - Invalid Or Missing Data For External Access - AutoCodes.com — U1199 Code - Invalid Or Missing Data For External Access

What does this mean?

What are the Possible Causes of the DTC U1199?

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

How to Fix the DTC U1199?

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 U1199 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 U1199 code?

Need more information on how to fix the U1199 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U1199 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 U1199 Code

1. What are the common symptoms of OBDII code U1199?

- Common symptoms include the check engine light being illuminated, issues with vehicle performance, and potential difficulty accessing certain diagnostic data.

2. What could cause the OBDII code U1199 to appear?

- The code may appear due to communication errors between external diagnostic tools and the vehicle's onboard computer system, faulty wiring or connectors, or issues with the external access module.

3. How can I diagnose the OBDII code U1199?

- Diagnosis typically involves using a professional OBDII scanner to retrieve the specific error code, checking for any visible wiring or connector issues, and testing the external access module if necessary.

4. Are there any simple checks I can perform to potentially resolve the U1199 code?

- Yes, you can start by ensuring all wiring and connectors related to external diagnostic access are secure and undamaged. Resetting the error code and retesting the system may also help.

5. Can the U1199 code be triggered by a loose gas cap?

- While a loose gas cap is more commonly associated with evaporative emission system codes, it is unlikely to directly trigger the U1199 code related to missing or invalid external access data.

6. Is it safe to continue driving with the U1199 code present?

- It is generally safe to drive with the U1199 code as long as the vehicle is not experiencing any significant performance issues or other related problems. However, it is recommended to address the underlying cause promptly.

7. How much does it usually cost to repair the U1199 code?

- The cost of repairing the U1199 code can vary depending on the root cause of the issue. Simple fixes like checking and securing connections may be low-cost, while replacing faulty components could be more expensive.

8. Can a DIY enthusiast fix the U1199 code at home?

- DIY enthusiasts with experience in automotive diagnostics and repair may be able to address the U1199 code at home, particularly if the issue is related to wiring or connectors. However, more complex problems may require professional assistance.

9. Will disconnecting the battery reset the U1199 code?

- Disconnecting the battery may reset the check engine light temporarily, but it will not necessarily resolve the underlying issue causing the U1199 code. It is recommended to diagnose and address the root cause of the problem.

10. How long does it typically take to repair the U1199 code?

- The time taken to repair the U1199 code can vary based on the complexity of the underlying issue. Simple fixes may take a short amount of time, while more involved repairs could require additional diagnostics and labor.