BMW DTC P21C5 – Reductant Level Sensor ‘A’ Stuck
DTC P21C5 meaning on BMW
The DTC P21C5 error code on a BMW indicates an issue with the Reductant Level Sensor ‘A’ being stuck. This sensor is responsible for monitoring the level of the diesel exhaust fluid (DEF), also known as AdBlue, in the vehicle’s emission control system.
BMW DTC P21C5 symptoms
Symptoms of the DTC P21C5 code on a BMW may include the malfunction indicator lamp (MIL) or check engine light illuminating on the dashboard. Additionally, the vehicle may experience reduced engine performance or fail to start due to the emission control system being affected.
BMW DTC P21C5 causes
The DTC P21C5 code on a BMW is commonly caused by a faulty Reductant Level Sensor ‘A’ or issues with the wiring/connectors associated with the sensor. Contamination or blockages in the DEF tank can also lead to this error code.
BMW DTC P21C5 seriousness
The DTC P21C5 code should not be ignored as it can lead to increased emissions and potential non-compliance with environmental regulations. Driving with this fault may also result in reduced fuel efficiency and engine performance.
How to diagnose DTC P21C5 on BMW
To diagnose the DTC P21C5 code on a BMW, a diagnostic scan tool can be used to retrieve the specific fault codes stored in the vehicle’s engine control module (ECM). A visual inspection of the Reductant Level Sensor ‘A’ and its wiring for any visible damage or corrosion is also recommended.
How to fix DTC P21C5 on BMW
Fixing the DTC P21C5 code on a BMW may involve replacing the Reductant Level Sensor ‘A’ if it is found to be faulty. Checking and cleaning the DEF tank for any contamination or blockages is also essential. Ensure all wiring and connectors associated with the sensor are in good condition.
How to erase DTC P21C5 on BMW
After fixing the underlying issue causing the DTC P21C5 code on a BMW, the error code can be erased using a diagnostic scan tool. Clearing the fault codes will reset the check engine light and allow the vehicle’s emission control system to operate normally.
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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