BMW DTC U1871 – Drive Motor ‘B’ Control Module Lost Communication With ECM via HS-CAN
DTC U1871 meaning on BMW
DTC U1871 on a BMW indicates that the Drive Motor ‘B’ Control Module has lost communication with the Engine Control Module (ECM) via the High-Speed Controller Area Network (HS-CAN) bus. This communication error can disrupt the proper functioning of the drive motor control system.
BMW DTC U1871 symptoms
Symptoms of DTC U1871 on a BMW may include:
- Check Engine Light (CEL) illuminated
- Reduced power or performance
- Difficulty shifting gears
- Vehicle may go into limp mode
BMW DTC U1871 causes
Possible causes of DTC U1871 on a BMW include:
- Faulty Drive Motor ‘B’ Control Module
- Wiring or connection issues between the control modules
- ECM software or hardware issues
BMW DTC U1871 seriousness
DTC U1871 should be addressed promptly as it can lead to drivability issues and potential safety concerns. Ignoring this fault may result in further damage to the vehicle’s drive motor control system.
How to diagnose DTC U1871 on BMW
To diagnose DTC U1871 on a BMW, follow these steps:
- Use a diagnostic scanner to retrieve the fault codes
- Inspect the wiring and connections between the Drive Motor ‘B’ Control Module and ECM
- Check for any visible damage or corrosion in the wiring harness
- Perform a communication test between the modules using a diagnostic tool
How to fix DTC U1871 on BMW
To fix DTC U1871 on a BMW, consider the following:
- Repair or replace any damaged wiring or connectors
- If the Drive Motor ‘B’ Control Module is faulty, replace it with a new one
- Update the ECM software if necessary
How to erase DTC U1871 on BMW
To erase DTC U1871 on a BMW, use a diagnostic scanner to clear the fault codes stored in the system’s memory. After fixing the underlying issue, ensure that the repair is successful by performing a test drive and re-scanning for any remaining fault codes.
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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