BMW DTC U0166 – Lost Communication With Auxiliary Heater Control Module
DTC U0166 meaning on BMW
The DTC U0166 code on a BMW indicates a communication error between the vehicle’s main control module and the auxiliary heater control module. This error typically occurs when the main control module is unable to establish communication with the auxiliary heater control module.
BMW DTC U0166 symptoms
Symptoms of the DTC U0166 code on a BMW may include:
- Malfunctioning or non-responsive auxiliary heater
- Check Engine Light (CEL) illuminated on the dashboard
- Loss of control over the auxiliary heater functions
BMW DTC U0166 causes
The common causes of the DTC U0166 code on a BMW are:
- Defective auxiliary heater control module
- Wiring issues or loose connections between the main control module and the auxiliary heater control module
- Faulty main control module
BMW DTC U0166 seriousness
The DTC U0166 code is not typically considered a serious issue that affects the overall drivability of the vehicle. However, it can impact the functionality of the auxiliary heater system, especially in colder climates.
How to diagnose DTC U0166 on BMW
To diagnose the DTC U0166 code on a BMW, you can follow these steps:
- Use a diagnostic scanner to retrieve the fault codes stored in the vehicle’s system
- Inspect the wiring and connections between the main control module and the auxiliary heater control module for any damage or loose connections
- Test the auxiliary heater control module for functionality and proper communication
- If necessary, perform a continuity test on the wiring harness to identify any open circuits
How to fix DTC U0166 on BMW
To fix the DTC U0166 code on a BMW, you can try the following solutions:
- Inspect and repair any damaged wiring or loose connections between the main control module and the auxiliary heater control module
- Replace the faulty auxiliary heater control module if it is determined to be the cause of the communication error
- If the main control module is faulty, consider replacing or reprogramming it as needed
How to erase DTC U0166 on BMW
To erase the DTC U0166 code on a BMW, you can use a diagnostic scanner to clear the fault codes stored in the vehicle’s system. Once the issue has been resolved and the fault codes have been cleared, the Check Engine Light should turn off.
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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