P2201Powertrain
NOx sensor (bank 1) — reading out of range
Where to start
The nitrogen oxide sensor reports implausible values. It differs from P2200 in that the link is there but the unit does not believe the numbers. A common cause is not the sensor but empty or diluted urea solution.
A code is not a diagnosis. It says which check failed, not which part to replace. Clearing it without repair only means the car will report it again in a few trips.
How to put together a report a mechanic will actually read
We have a detailed piece on thisAdBlue and urea: codes P203B, P2047, P204F, P20EE
How the code is built
Letter — the systemPowertrain: engine and transmission
Common or the maker's ownGeneric code, second group
Which part of the engineFuel and air metering: injectors
Number of the faultThe serial number inside that group — it does not say how serious the fault is
All codes in «Fuel and air metering: injectors»
How the app helps
CarScan reads this code from your car through an OBD-II adapter, shows whether it is active now or only stored, names the module that reported it, and puts it into a plain-text report for your mechanic.