Emissions

P2211 — NOx Sensor Positive Current Control Circuit High (Bank 1 Sensor 1)

Severity: medium Drive with care, to a shop

What P2211 means

The engine control module detected a voltage or current that is too high in the positive current control circuit of the bank 1 sensor 1 nitrogen oxide (NOx) sensor. The NOx sensor measures NOx in the exhaust and helps the SCR system (AdBlue/DEF injection) dose reductant accurately. With a circuit or sensor fault, the ECM cannot judge how well the catalyst is working.

Symptoms

  • Check engine light or SCR/AdBlue warning on
  • Exhaust treatment system fault message
  • Emissions monitor failure during testing
  • Start countdown on some vehicles
  • Torque limitation on some vehicles

Possible causes

  1. Failed NOx sensor (probe)
  2. Open in the sensor control circuit
  3. Broken or damaged wiring
  4. Wiring shorted to positive
  5. Corroded or damaged connector terminals
  6. Less commonly, an ECM or sensor control module fault

How to diagnose

  1. Scan for all codes and freeze frame data, noting any other SCR-related codes
  2. View NOx sensor values and dosing system status on a scan tool
  3. Check reductant level and quality data where available
  4. Inspect the sensor connector and harness for chafing, moisture, heat damage or corrosion
  5. Test the circuit for opens and shorts to power and ground using the factory wiring diagram
  6. Verify power and ground supply to the NOx sensor
  7. Inspect the dosing valve, lines and heater operation
  8. Check for OEM technical bulletins and software updates

Common fixes

  • Repair damaged wiring or replace the connector
  • Clean the terminals and remove moisture from the connector
  • Replace the NOx sensor if the circuit tests good
  • Update ECM software if the manufacturer offers it
  • Clear codes and verify the repair on a road test

Questions and answers

What does P2211 mean?

It indicates a high signal in the positive current control circuit of the bank 1 sensor 1 NOx sensor. The usual culprits are the sensor itself or its wiring.

Can I drive with P2211?

For a short time, yes, but the SCR system may go into a limp mode with reduced power or a no-restart condition. Get it diagnosed soon.

Do I always need a new NOx sensor?

No. Check the wiring, connector and power supply first, since an open or a short to positive can set the same code. Replace the sensor only if the circuit is good.

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.