Emissions

P2206 — NOx Sensor Heater Control Circuit High (Bank 1 Sensor 1)

Severity: medium Drive with care, to a shop

What P2206 means

The engine control module powers a heater inside the nitrogen oxide (NOx) sensor so the sensing element reaches operating temperature quickly. P2206 sets when the voltage in the heater control circuit is higher than expected. The cause can be the sensor itself, its wiring, or its control unit. Until the sensor works properly, the SCR (AdBlue/DEF) system cannot dose reductant accurately.

Symptoms

  • Check engine light on
  • SCR or AdBlue/DEF warning displayed
  • Power or torque limitation on some vehicles
  • SCR operation limited until the system warms up
  • Possible engine start countdown before lockout

Possible causes

  1. Failed NOx sensor (heater or internal electronics)
  2. Heater circuit shorted to voltage
  3. Damaged wiring harness insulation
  4. Corroded, loose or partly unseated connector
  5. Failed NOx sensor control module
  6. ECM software issue (uncommon)

How to diagnose

  1. Scan all codes and freeze frame data and look for other SCR or NOx faults
  2. View NOx sensor readings plus heater and dosing system status on a scan tool
  3. Check the reductant (DEF) level and quality
  4. Inspect the sensor connector and harness for chafing, corrosion, melting or poor pin fit
  5. Test the heater power and control circuit with a multimeter per the factory diagram, looking for a short to voltage
  6. Verify sensor supply voltage and ground
  7. Check for technical service bulletins and software updates for the vehicle

Common fixes

  • Repair damaged wiring or replace the connector
  • Clean the terminals and secure the connector fully
  • Replace the NOx sensor (with its control module if supplied together)
  • Update ECM software per the manufacturer's bulletin
  • Clear codes and verify SCR operation after repair

Questions and answers

What does P2206 mean?

The ECM detected too high a voltage in the Bank 1 NOx sensor heater control circuit. The sensor or its wiring is the most common cause.

Can I drive with P2206?

For a short time, yes, but emissions are higher and some vehicles limit power or start a restart countdown. Get it diagnosed soon.

Should I replace the NOx sensor right away?

No. Check the connector, harness and sensor supply first. Replace the sensor only if the wiring is good and the code returns.

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.