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P2200 – NOx Sensor Circuit Bank 1 (OBD2)

P2200 means "NOx Sensor Circuit Bank 1". The control unit has detected a fault in the electrical circuit of the NOx sensor: the signal or control current is missing or outside the expected window. The code does not say whether the value is too high or too low, so the wiring and the component itself both have to be checked.

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P2200 quick summary

Fault codeP2200
MeaningNOx Sensor Circuit Bank 1
SystemPowertrain (Engine & Transmission)
VehiclesGeneric OBD2
SeverityMedium
Can I drive?Usually yes, but the AdBlue system may stop dosing and some vehicles start a countdown before limiting the engine or preventing a restart. Have it repaired soon.
Repair cost€100 – €800

How the NOx sensor works

The NOx sensor measures nitrogen oxides in the exhaust so the control unit can run and monitor the SCR (AdBlue) system or NOx storage catalyst; these codes mean the sensor, its heater or its circuit has a fault.

Modern diesels – and some petrol engines with a NOx storage catalyst – have one or two NOx sensors in the exhaust: one before and one after the SCR catalyst. Each sensor has its own small control module on the cable that heats the sensor element and sends the NOx value over the CAN bus.

The engine control unit uses the upstream sensor to calculate how much AdBlue to inject and the downstream sensor to check that the catalyst works. A faulty sensor can therefore cause AdBlue system warnings, a countdown to a no-start on some vehicles and failed emissions tests.

NOx sensors are exposed to high temperatures, condensation and soot. Common faults are a failed heater, a cracked sensor element, a damaged control module or connector and a sensor that is slowly drifting.

Bank 1 is the side of the engine that contains cylinder 1. In-line engines (three, four, five or six cylinders in a row) have only bank 1.

Symptoms of P2200

  • Check Engine light
  • AdBlue or emission system warning
  • Countdown message ("No start in … km")
  • Higher AdBlue consumption or no AdBlue consumption
  • Failed emissions test

Most common causes of P2200 (most likely first)

Mechanic's Pro Tip

On many vehicles the upstream and downstream NOx sensors look identical but have different part numbers. Check the part number carefully – the wrong sensor causes plausibility codes straight away.

  1. 1.Damaged wire or loose, corroded connector at the NOx sensor

    Most likely

    Green or white corrosion, pushed-back pins and chafed insulation near hot or moving parts are the most common findings.

  2. 2.Faulty NOx sensor

    An internal break or short in the component itself.

  3. 3.Blown fuse or missing supply voltage

    If several codes appeared at the same time, check the shared fuse, relay or ground point first.

  4. 4.Exhaust leak near the sensor

  5. 5.CAN communication or supply fault

Step-by-step diagnostic guide

  1. 1

    Read codes and NOx values

    Read the engine control unit and check both NOx sensor readings and their status (ready, heater on) in live data with a warm engine.

  2. 2

    Check the circuit with a multimeter

    With the ignition off, unplug the NOx sensor and the control unit connector (or back-probe), then check each wire between them for continuity and for shorts to ground and to battery voltage. Compare the component's resistance or supply voltage with the value in the repair manual.

    Multimeter: Wire continuity: below about 1 Ω. Wire to ground with both connectors unplugged: no continuity. Supply/reference with ignition on: usually 5 V for sensors, battery voltage for actuators.

  3. 3

    Check supply and CAN

    Check the supply and ground at the sensor control module and look for CAN communication codes.

    Multimeter: Most NOx sensor modules are supplied with battery voltage and communicate over CAN; check the specification for your vehicle.

  4. 4

    Inspect connector and wiring

    Check the connector for water and corrosion and the cable for heat damage.

  5. 5

    Check for exhaust leaks

    Look for leaks near the sensor that let in fresh air.

  6. 6

    Replace and adapt

    Replace the sensor (with its control module), clear codes and run any NOx sensor adaptation or system test with the scan tool.

Frequently asked questions

Can I keep driving with P2200?

Usually yes, but the AdBlue system may stop dosing and some vehicles start a countdown before limiting the engine or preventing a restart. Have it repaired soon.

How much does it cost to fix P2200?

Typical repair costs are 100 € – 800 €, depending on the cause and the vehicle. The most common fixes are: damaged wire or loose, corroded connector at the NOx sensor; faulty NOx sensor; blown fuse or missing supply voltage. Always confirm the cause with the tests above before buying parts.

Can I drive with a NOx sensor fault?

Usually for a while, but many diesels start a countdown and then limit power or prevent a restart. Repair it before the countdown ends.

Can a NOx sensor be cleaned?

No. If the sensor or its heater has failed, it must be replaced.

What is the difference between P2200 and similar codes?

P2200 belongs to a group of codes for the same component that differ in the type or location of the fault: P2201 – NOx Sensor Range/Performance Bank 1; P2202 – NOx Sensor Circuit Low Bank 1; P2203 – NOx Sensor Circuit High Bank 1; P2204 – NOx Sensor Circuit Intermittent Bank 1; P2205 – NOx Sensor Heater Control Circuit/Open Bank 1; P2206 – NOx Sensor Heater Control Circuit Low Bank 1. The tests on this page apply to the whole group; the type of fault tells you where to start.

Related fault codes

This guide is for information only. Working on vehicles can be dangerous — if you are unsure, have the car checked by a qualified mechanic. Values can differ between model years; always check the manufacturer's repair information.