U1221 – BMW DTC

BMW DTC U1221 – Message Monitoring 10ms Task Check Sum Error

DTC U1221 meaning on BMW

The DTC U1221 code on BMW vehicles indicates a Message Monitoring 10ms Task Check Sum Error. This error occurs when the checksum of a message being monitored does not match the expected value, suggesting a communication issue within the vehicle’s network.

BMW DTC U1221 symptoms

Symptoms of the BMW DTC U1221 code may include:

• Check Engine Light (MIL) illuminated
• Communication errors with various vehicle systems
• Performance issues

BMW DTC U1221 causes

Common causes of the BMW DTC U1221 code include:

• Interference in the communication network
• Faulty control modules
• Wiring or connection issues

BMW DTC U1221 seriousness

The DTC U1221 error code should not be ignored as it can lead to communication problems between various vehicle systems. Ignoring this issue may result in performance issues or potential safety concerns.

How to diagnose DTC U1221 on BMW

To diagnose the DTC U1221 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 communication network.
3. Check for any loose or damaged components that may be causing the issue.

How to fix DTC U1221 on BMW

To fix the DTC U1221 code on a BMW, consider the following:

1. Repair any damaged wiring or connections in the communication network.
2. Replace any faulty control modules that may be causing the issue.
3. Clear the fault codes using a diagnostic scanner after the repairs have been made.

How to erase DTC U1221 on BMW

To erase the DTC U1221 code on a BMW, follow these steps:

1. Use a diagnostic scanner to clear the fault codes stored in the vehicle’s computer.
2. Ensure that the underlying issue causing the code has been resolved before clearing the code.
3. Perform a test drive to confirm that the code does not reappear.

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

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