Diagnose BMW CAN Network Fault

Published by YOUCANIC Automotive Experts 
Last Updated Nov 21, 2018 

In this guide, we take a look at how to troubleshoot BMW CAN Network. Learn what CAN Network does, common problems, how to read/clear codes from CAN Network and perform tests yourself.

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What is BMW CAN Network? 

CAN stands for Controller Area Network integrates BMW control units in one network improving communication speed while reducing the number of wires needed for s to communicate. BMW CAN network makes it easy to perform diagnostics using a BMW OBD-II scanner. 

BMW CAN network connect various  s including transmission (EGS), Engine Control Module (DME), antilock brake (ABS), traction control/stability control system (DSC), electronic steering, climate control system, lighting control  and many more. BMW vehicles may have more than one CAN network. Examples of BMW CAN Networks:

  • DT – Can (powertrain CAN)
  • F-Can (suspension CAN)
  • K-Can (body CAN)
  • MOST (Media Oriented System Transport)
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Symptoms 

List of possible symptoms you may notice if the CAN Network or one of its components fails. 

  • No communication between s
  • No response from a single
  • No communication via the OBD-II port
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Common Problems

Possible problems that can trigger fault codes in the CAN Network . 

  • Damaged or corroded CAN wires
  • Poor ground connection
  • Failed Control Module
  • Water Damage
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Troubleshoot BMW CAN Network

Read / clear CAN Network Fault Codes

If you are experiencing problems a good starting point is to read fault codes from the CAN Network . If any code is showing PRESENT status the problem needs to be fixed before the code can be cleared. 

What you will need

A diagnostic scanner that is capable of reading, clearing and performing bi-directional tests on BMW vehicles. You must verify that the scanner that you use supports your BMW model and year. Full system scanners that are known to work on BMW vehicles can range in price from $150 to $800 USD.  

List of scanners that read and clear BMW CAN Network fault codes.

These are only a few examples. Many diagnostic scanners allow you to read and clear BMW CAN Network fault codes. To learn about OBD2 scanners that work on BMWs check the article on Choosing the best OBD2 scanner for BMW. 

Instructions

  1. Plug in the OBD-II scanner into the diagnostic port under the dashboard. diagnose bmw CAN Network fault code via obd2 port

     

  2. Turn on the ignition, don't start the engine. turn on bmw ignition to read CAN Network fault codes

     

  3. Turn on the scanner and select your BMW chassis.  Next, Select Control Units menu. bmw CAN Network control unit   reading codes

     

  4. Select Body then CAN Communication Analysis.
  5. Once you enter the CAN Network , you will be able to do the following. 
    • Read Codes from CAN Network 
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CAN Network Fault Codes 

There are hundreds of fault codes that can be related to BMW CAN Network. Below are a few examples of codes stored in BMW CAN Network.

  • CDA9 - DME Message A/C Request
  • E5C4 - CID K CAN wire fault
  • E71E  - IHKA Message Torque 
  • FFFF - CANSYS Communication Fault

These fault codes will show during netwrok analysis but will be stored in the corresponding control unit as well. 

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Additional Resources

  1. CAN Bus System and Technology - BMW Motorrad UK
  2. How to Diagnose a CAN Network - AA1Car.com
  3. Investigations on a BMW X5 Can Bus system - techtalk.ie
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