AutoCodes – Generic – U1156

U1156 Code - Invalid Or Missing Data For Digital Signal Processing

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: U1156 indicates Invalid Or Missing Data For Digital Signal Processing.
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 5,662

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 24, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1156 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 U1156 - Invalid Or Missing Data For Digital Signal Processing - AutoCodes.com — U1156 Code - Invalid Or Missing Data For Digital Signal Processing

What does this mean?

What are the Possible Causes of the DTC U1156?

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

How to Fix the DTC U1156?

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 U1156 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 U1156 code?

Need more information on how to fix the U1156 code? Get Access to Factory Service Manuals

Need Help with the Code?

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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 U1156 Code

What does the OBDII code U1156 mean?

The U1156 code indicates "Invalid or Missing Data for Digital Signal Processing," meaning there is a communication issue between control modules in the vehicle.

What are the common symptoms of the U1156 code?

Symptoms may include a check engine light, erratic vehicle performance, malfunctioning electronic systems, or no noticeable symptoms at all.

What causes the U1156 code to appear?

The code is often triggered by faulty wiring, damaged connectors, a failing control module, or temporary communication glitches between modules.

Can a weak battery cause the U1156 code?

Yes, a weak or failing battery can cause communication issues between modules and trigger the U1156 code.

How can I diagnose the U1156 code?

Start by checking for loose or corroded connections and inspecting the wiring. You can also use a scan tool to verify communication between modules.

Is the U1156 code serious?

It depends on the symptoms. If it affects vehicle performance, it should be addressed promptly, but if there are no noticeable issues, it may be less urgent.

Can I drive with the U1156 code active?

While it might be possible to drive, ignoring the code could lead to further communication issues or malfunctions, so it's best to address it as soon as possible.

How do I fix the U1156 code?

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

Do I need a professional to fix the U1156 code?

If you're familiar with electrical diagnostics, you might troubleshoot it yourself, but more complex issues like module replacement may require professional help.

How can I prevent the U1156 code from recurring?

Regular vehicle maintenance, including checking for corroded connectors and ensuring all software is up to date, can help prevent this code from recurring.