BMW DTC P221B – NOx Sensor 1/2 Correlation (Bank 2)
DTC P221B meaning on BMW
The DTC P221B code on a BMW indicates a NOx (Nitrogen Oxide) sensor 1/2 correlation issue in Bank 2. This means that there is a discrepancy between the readings of the two NOx sensors located in Bank 2 of the vehicle’s exhaust system.
BMW DTC P221B symptoms
Symptoms of a DTC P221B NOx sensor correlation problem in a BMW may include:
- Check Engine Light (MIL) illuminated
- Reduced engine performance
- Increased fuel consumption
- Failed emissions test
BMW DTC P221B causes
Common causes of the DTC P221B NOx sensor 1/2 correlation issue in a BMW include:
- Defective NOx sensors
- Wiring or connector issues
- Exhaust system leaks
- Software or calibration problems
BMW DTC P221B seriousness
The DTC P221B code should not be ignored as it can lead to increased emissions, reduced engine efficiency, and potential damage to the catalytic converter. It is important to address this issue promptly to ensure the vehicle operates efficiently and meets emission standards.
How to diagnose DTC P221B on BMW
To diagnose a DTC P221B NOx sensor correlation problem on a BMW, a mechanic may perform the following steps:
- Use a diagnostic scanner to retrieve the fault codes
- Inspect the NOx sensors and their wiring for damage or corrosion
- Check for exhaust leaks in Bank 2 of the vehicle
- Perform a software update or calibration if necessary
How to fix DTC P221B on BMW
To fix a DTC P221B NOx sensor 1/2 correlation issue on a BMW, the following steps may be taken:
- Replace the faulty NOx sensors in Bank 2
- Repair any damaged wiring or connectors
- Address any exhaust leaks in Bank 2
- Perform a software update or calibration as needed
How to erase DTC P221B on BMW
After the DTC P221B NOx sensor correlation issue has been fixed on a BMW, the fault codes can be erased using a diagnostic scanner. This will reset the Check Engine Light and clear the code from the vehicle’s memory. It is important to ensure that the underlying issue has been resolved before clearing the 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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