KlaroFault codeP2201
MODERATENOx Sensor Circuit Range/Performance (Bank 1 Sensor 1)
What this code means
NOx Sensor Circuit Range/Performance (Bank 1 Sensor 1).
“Bank 1” is the side of the engine that holds cylinder number 1; “Bank 2” only exists on V and flat engines. An in-line engine has a single bank.
P2201 is a generic code: it means the same thing on every make. P2201 belongs to family P22xx — Fuel and air metering sensors. Its page explains how to read a code and groups all its codes by part.
Type of fault
The signal stays within its electrical limits, but its value is not plausible: it does not match what the control unit expects given the other sensors. The sensor may be drifting with age, but it may also be faithfully measuring a real mechanical problem — a leak, a blockage, an air leak. Replacing the sensor without checking does not always clear the fault.
NOx sensor
The NOx sensor measures the nitrogen oxides in the exhaust. Diesels with AdBlue usually have two, before and after the SCR catalyst, and some petrol engines have one. Each sensor carries its own small control module on its wiring.
What you notice
Usually an emissions warning, sometimes an AdBlue warning or reduced power; the car may fail the emissions test.
How to check it
Check the connector and the module, mounted under the car where they are exposed to water and road salt. A NOx sensor ages and drifts: when its module reports an internal fault, the sensor is replaced together with its module.
What to do
Have it checked this week. The car remains usable, but the fault will not clear itself and will fail the roadworthiness test.
Clearing a code switches the light off but repairs nothing: if the fault remains, the code comes back. Clearing a fault code yourself →
How to read this code
- PPowertrain
- 2standardised code
- 2Fuel and air metering sensors
- 01P2201
