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EmissionsSeverity Medium: diagnose soon

P2203NOx Sensor Circuit High (Bank 1)

What it means

The NOx sensor (bank 1) signal is too high.

Symptoms

  • Emissions or AdBlue warning light
  • Possibly a countdown to a no-restart condition

Common causes

  • Failed NOx sensor (common)
  • Wiring or connector fault (heat damage)
  • Missing supply or CAN fault to the sensor module
  • Exhaust leak near the sensor

What to check first

  1. Check supply, ground and CAN wiring at the sensor module
  2. Read the NOx sensor values and status bits
  3. Check for exhaust leaks before replacing the sensor
Can I drive with P2203? Usually yes for a short distance, but performance or economy may suffer and the fault can get worse. Diagnose it soon.

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

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P2203: questions and answers

What does P2203 mean?

P2203: NOx Sensor Circuit High (Bank 1). The NOx sensor (bank 1) signal is too high.

What are the symptoms of P2203?

Emissions or AdBlue warning light. Possibly a countdown to a no-restart condition.

What causes P2203?

Failed NOx sensor (common). Wiring or connector fault (heat damage). Missing supply or CAN fault to the sensor module. Exhaust leak near the sensor.

How do you diagnose P2203?

1. Check supply, ground and CAN wiring at the sensor module 2. Read the NOx sensor values and status bits 3. Check for exhaust leaks before replacing the sensor

Can I drive with P2203?

Usually yes for a short distance, but performance or economy may suffer and the fault can get worse. Diagnose it soon.