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U1012 – What Does It Mean and How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


U1012 is an OBD-II Code that refers to Invalid Internal Control Module Monitoring Data Received From Anti-Lock Brake System Control Module


A U1012 code is a diagnostic trouble code that occurs when the other control modules on the vehicle are not communicating with each other. In this instance the Controller Area Network bus communications, or simply CAN indicates there’s a loss of communication with the ABS control module. 

The CAN bus is a high-speed serial data bus used for communication between various control modules in the vehicle. When one of these modules fails to communicate with the others, it can cause the U1012 code to be stored.


Common causes for this code include:

  • Bad Anti-Lock Brake System (ABS) Control Module
  • Open or shorted Anti-Lock Brake System (ABS) Control Module harness
  • Poor electrical connection in Anti-Lock Brake System (ABS) Control Module circuit


The symptoms of a U1012 code are:


To diagnose a U1012 DTC code, a technician would:

  1. Scan for codes in the ECM and look at the freeze frame data for failure.
  2. Visually inspect all related wiring and connectors.
  3. Check the battery voltage and condition.
  4. Check the charging system output.
  5. If all previous steps check out, then the next step would be to test the ABS control module itself with a scan tool that can read live data from the module. If there is no communication with the module, then it will need to be replaced.

Also Read: How Do You Test A Brake Master Cylinder?

Common mistakes

The following are some of the most common mistakes that a technician may make when diagnosing a U1012 code:

  • Not thoroughly inspecting all the wiring and connectors
  • Failing to check the battery voltage and condition
  • Failing to check the charging system output
  • Failing to check Manufacturer Factory Service Manuals
  • Replacing the ABS control module without testing it first

How serious is this?

A U1012 code is a serious code and should be addressed as soon as possible. There may be a loss of power, engine performance, or safety features depending on the severity of the issue.

What repairs can fix the code?

repair manuals

The following are solutions that may fix this problem:

  • Repair or replace any damaged wiring and connectors
  • Replace the ABS control module
  • Install a new battery
  • Repair or replace the charging system
  • Flash the ECM with updated software
  • See Manufacturer Factory Service Manuals

Related codes

A U1012 is related to and may be accompanied by the following codes:

U0100-U0199 – Network Communication Codes

B1042 – Right Frontal Air Bag Deployment Control Circuit Resistance Too High

B1046 – Left Frontal Air Bag Deployment Control Circuit Resistance Too Low

B1048 – Right Frontal Air Bag Deployment Control Circuit Open


In conclusion, the U1012 code is a diagnostic trouble code that refers to a problem with the communication between the various control modules on the vehicle. This can be caused by a variety of issues, such as a bad ABS control module, damaged wiring or connectors, or a problem with the battery or charging system. If you experience any of the symptoms associated with this code, it’s important to have it diagnosed and repaired as soon as possible to avoid further damage to your vehicle.