U122B – BMW DTC

BMW DTC U122B – Lost Communication With Segment Synchronous Message From Slave

DTC U122B meaning on BMW

The DTC U122B code on a BMW indicates a communication error with the Segment Synchronous Message from a slave module. This means that the control module in question is not receiving the expected data or signals from the specified segment, leading to a loss of communication.

BMW DTC U122B symptoms

Symptoms of the DTC U122B code on a BMW may include:

• Check Engine Light (CEL) illuminated on the dashboard
• Issues with transmission shifting
• Problems with engine performance
• Loss of communication with certain vehicle systems

BMW DTC U122B causes

The potential causes of the DTC U122B code on a BMW include:

• Faulty wiring or connections in the communication network
• Defective control module or segment module
• Interference from other electronic devices
• Software issues within the control modules

BMW DTC U122B seriousness

The DTC U122B code should not be ignored as it can lead to communication breakdown between critical vehicle systems. Ignoring this code may result in performance issues, safety concerns, and potential damage to the vehicle components.

How to diagnose DTC U122B on BMW

To diagnose the DTC U122B code on a BMW, follow these steps:

1. Use a diagnostic scanner to retrieve the fault codes stored in the vehicle’s computer.
2. Inspect the wiring and connections related to the affected segment module.
3. Check for any visible signs of damage or corrosion in the communication network.
4. Perform a module scan to identify the specific control module that is not communicating.

How to fix DTC U122B on BMW

To fix the DTC U122B code on a BMW, consider the following steps:

1. Repair any damaged wiring or connections in the communication network.
2. Replace the faulty control module or segment module, if necessary.
3. Update the software in the control modules to address any compatibility issues.
4. Clear the fault codes using a diagnostic scanner after completing the repairs.

How to erase DTC U122B on BMW

To erase the DTC U122B code on a BMW, follow these steps:

1. Connect a diagnostic scanner to the vehicle’s OBD-II port.
2. Select the ¨Erase Codes¨ or ¨Clear Codes¨ option on the scanner.
3. Follow the on-screen prompts to confirm the deletion of the fault codes.
4. Once the codes are cleared, disconnect the scanner and start the vehicle to ensure the CEL is no longer illuminated.

Recommended tools & DTC Scanners for BMW

Best Diagnostic App for modern BMWs: BimmerLink

Recommended Bluetooth adapter for Bimmerlink: OBDLink CX

Cable adapter for Bimmerlink: Enet Cable USB Type C

For older BMWs we recommend: Autel AutoLink AL319 (2024 version)

Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter

Some of the links on this page may be affiliate links, which means we may earn a small commission if you make a purchase. This helps us keep our DTC database up to date and provide valuable content for free. We only recommend products that we have tested and believe to be the best in their class.