Emissions

P2212 — NOx Sensor Positive Current Control Circuit Open (Bank 2 Sensor 1)

Severity: medium Drive with care, to a shop

What P2212 means

The engine control unit monitors the positive current control circuit of the nitrogen oxide (NOx) sensor on bank 2, sensor 1. This sensor measures NOx in the exhaust, and the SCR system uses the data to calculate how much AdBlue (reductant) to inject. P2212 is set when the control unit detects an open circuit or gets no valid signal from the sensor.

Symptoms

  • Check engine light on
  • SCR or AdBlue warning on the dash
  • Other bank 2 SCR or NOx codes
  • Possible torque limitation
  • Start countdown on some vehicles
  • Higher NOx emissions

Possible causes

  1. Failed bank 2 sensor 1 NOx sensor
  2. Open circuit in the sensor wiring
  3. Corroded or loose connector near the exhaust
  4. Damaged or chafed wiring harness
  5. Poor connection or weak ground
  6. Faulty NOx sensor control module (where separate)

How to diagnose

  1. Read all codes and freeze frame data and note any other SCR codes
  2. View NOx sensor values and dosing system status on a scan tool
  3. Check reductant level and quality
  4. Inspect the sensor connector for moisture, corrosion or heat damage
  5. Test the harness for opens and shorts to ground or power
  6. Check sensor power, ground and heater operation
  7. Inspect the dosing valve, lines and SCR heating
  8. Look for technical service bulletins and ECU software updates

Common fixes

  • Repair or replace the damaged section of wiring
  • Clean or replace the sensor connector
  • Replace the bank 2 NOx sensor
  • Update ECU software per a bulletin
  • Clear codes and confirm the fault does not return

Questions and answers

What does P2212 mean?

The control unit found an open circuit in the positive current control line of the bank 2 sensor 1 NOx sensor. The sensor, its connector or its wiring is the usual culprit.

Can I drive with P2212?

Briefly, yes, but fix it soon. Some vehicles limit torque or start a countdown that can end in a no-start condition.

Should I replace the NOx sensor right away?

No. Check the connector, harness and sensor power first. Open circuits and corroded contacts are common, and the sensor itself is expensive.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.