BMW DTC C12A9 – Transfer Case Control Module Power Supply Circuit ‘B’ /Open
DTC C12A9 meaning on BMW
The DTC C12A9 code on a BMW indicates a fault in the Transfer Case Control Module Power Supply Circuit ‘B’, specifically an open circuit. This means that there is a break or discontinuity in the electrical path that supplies power to the transfer case control module.
BMW DTC C12A9 symptoms
Symptoms of the DTC C12A9 code on a BMW may include:
- Warning lights on the dashboard related to the transfer case
- Loss of functionality in the transfer case system
- Difficulty shifting between drive modes
BMW DTC C12A9 causes
Common causes of the DTC C12A9 code on a BMW include:
- Corroded or damaged wiring in the power supply circuit
- A faulty transfer case control module
- Loose or poor connections in the circuit
BMW DTC C12A9 seriousness
The DTC C12A9 code should be addressed promptly as it can lead to a loss of control over the transfer case system, affecting the vehicle’s drivability and potentially causing further damage if left unresolved.
How to diagnose DTC C12A9 on BMW
To diagnose the DTC C12A9 code on a BMW, a mechanic would typically perform the following steps:
- Use a diagnostic scanner to retrieve the fault codes stored in the vehicle’s computer
- Inspect the power supply circuit for any visible damage or corrosion
- Check the connections to the transfer case control module for tightness and proper contact
- Test the transfer case control module for functionality
How to fix DTC C12A9 on BMW
To fix the DTC C12A9 code on a BMW, the following steps may be taken:
- Repair or replace any damaged wiring in the power supply circuit
- Ensure all connections to the transfer case control module are secure and free of corrosion
- Replace the transfer case control module if it is found to be faulty
How to erase DTC C12A9 on BMW
After the issue causing the DTC C12A9 code has been resolved, the code can be erased using a diagnostic scanner that has the capability to clear fault codes from the vehicle’s computer system.
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.