BMW DTC P1D21 – Electric A/C Compressor Control Module Internal Temperature Sensor ‘B’ Temperature Out of Range Low
DTC P1D21 meaning on BMW
DTC P1D21 on a BMW indicates an issue with the Electric A/C Compressor Control Module Internal Temperature Sensor ‘B’. Specifically, it means that the temperature reading from sensor ‘B’ is out of range on the low end.
BMW DTC P1D21 symptoms
Symptoms of DTC P1D21 on a BMW may include:
- Malfunctioning air conditioning system
- Reduced cooling performance
- Dashboard warning light related to the A/C system
BMW DTC P1D21 causes
Common causes of DTC P1D21 on a BMW include:
- Failed Electric A/C Compressor Control Module
- Wiring or connection issues with the temperature sensor ‘B’
- Internal fault within the temperature sensor ‘B’
BMW DTC P1D21 seriousness
The seriousness of DTC P1D21 on a BMW depends on the driving conditions and climate. While it may not directly affect the drivability of the vehicle, a malfunctioning A/C system can be uncomfortable, especially in hot weather.
How to diagnose DTC P1D21 on BMW
To diagnose DTC P1D21 on a BMW, a mechanic would typically:
- Use a diagnostic scanner to retrieve the fault codes
- Inspect the Electric A/C Compressor Control Module and its connections
- Test the temperature sensor ‘B’ for proper operation
How to fix DTC P1D21 on BMW
To fix DTC P1D21 on a BMW, the following steps may be taken:
- Replace the Electric A/C Compressor Control Module if faulty
- Repair any wiring or connection issues related to temperature sensor ‘B’
- Replace the temperature sensor ‘B’ if it is internally faulty
How to erase DTC P1D21 on BMW
To erase DTC P1D21 on a BMW, the fault codes can be cleared using a diagnostic scanner. Once the underlying issue has been addressed and fixed, the codes can be cleared to reset the system and turn off the warning light.
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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