Fault-Code Library · NOx sensing

P2201: NOx sensor circuit range / performance

A NOx sensor signal or its controller behavior is outside the expected operating range.

Fault-Code Library

Common symptoms

  • •Engine or AdBlue warning
  • •Restart countdown on some vehicles
  • •Emissions-system messages

Likely causes

  • •Failed NOx sensor or control module
  • •Wiring or connector heat damage
  • •Exhaust leak
  • •Incorrect temperature or dosing behavior

First checks

  • •Identify the exact sensor position
  • •Inspect wiring near the exhaust
  • •Compare sensor values after correct warm-up

Important

Manufacturer-specific subcodes are essential because several NOx sensors may be fitted.

A fault code identifies a detected condition, not a failed part. Confirm manufacturer-specific subcodes and live data.

Inspect first