BMW DTC P21CC – Reductant Control Module Supply Voltage High
DTC P21CC meaning on BMW
The Diagnostic Trouble Code (DTC) P21CC for BMW indicates an issue with the Reductant Control Module Supply Voltage being too high. The Reductant Control Module is responsible for managing the supply of the reducing agent (commonly known as AdBlue) in the Selective Catalytic Reduction (SCR) system of the vehicle.
BMW DTC P21CC symptoms
Symptoms of the DTC P21CC on a BMW may include:
- Check Engine Light (MIL) illuminated
- Reduced engine performance
- Possible limp mode activation
BMW DTC P21CC causes
Common causes of the DTC P21CC on a BMW include:
- Faulty Reductant Control Module
- Short circuit or open circuit in the wiring related to the Reductant Control Module
- Issues with the power supply to the Reductant Control Module
BMW DTC P21CC seriousness
The DTC P21CC should be addressed promptly as it can lead to increased emissions and potential damage to the SCR system if left unresolved. Ignoring this issue may also result in the vehicle failing emissions tests.
How to diagnose DTC P21CC on BMW
To diagnose the DTC P21CC 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 Reductant Control Module and related wiring for any visible damage
- Check the power supply to the Reductant Control Module for proper voltage
How to fix DTC P21CC on BMW
To fix the DTC P21CC on a BMW, the following steps may be taken:
- Replace the faulty Reductant Control Module if necessary
- Repair any damaged wiring or connectors related to the Reductant Control Module
- Ensure the power supply to the Reductant Control Module is functioning correctly
How to erase DTC P21CC on BMW
After addressing the underlying issue causing the DTC P21CC on a BMW, the fault codes can be cleared using a diagnostic scanner. This will reset the Check Engine Light and allow the vehicle’s computer to monitor the system for any new faults.
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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