Emissions

P2208 — NOx Sensor Heater Control Circuit High (Bank 2 Sensor 1)

Severity: medium Drive with care, to a shop

What P2208 means

The engine control module powers a heater inside the bank 2 nitrogen oxide (NOx) sensor so it reaches operating temperature quickly. P2208 sets when the heater control circuit reads higher voltage or current than expected. Without reliable NOx readings, the SCR system cannot dose reductant (DEF) correctly.

Symptoms

  • Check engine light on
  • SCR system inactive or inaccurate
  • Increased NOx emissions
  • Exhaust treatment or DEF warning message
  • Possible power reduction or restart warning

Possible causes

  1. Failed bank 2 NOx sensor (internal heater circuit)
  2. Heater control wire shorted to power
  3. Damaged or corroded wiring
  4. Corrosion or moisture in the sensor or NOx control module connector
  5. Faulty NOx sensor control module or ECM
  6. Open circuit or poor connection

How to diagnose

  1. Scan all codes and freeze frame data and note any other NOx or SCR codes
  2. Inspect the bank 2 NOx sensor connector and harness for chafing, moisture, corrosion and heat damage
  3. Check power and ground at the connector using the factory wiring diagram
  4. Measure heater resistance and compare with specification
  5. Test the wiring for a short to power and for opens
  6. Review sensor live data after warm-up
  7. If wiring is good, test the sensor control module and replace the sensor if needed

Common fixes

  • Clean and repair the connector terminals and remove moisture
  • Repair or replace damaged wiring
  • Replace the bank 2 NOx sensor
  • Replace the NOx control module or update ECM software per service bulletin
  • Clear the code and confirm it does not return on a test drive

Questions and answers

What does P2208 mean?

It means the bank 2 sensor 1 NOx sensor heater circuit reads high. The sensor, its wiring or the connector is the usual culprit.

Can I drive with P2208?

Usually for a short time, but emissions will be higher and some vehicles limit power. Do not put off the repair.

Should I replace the NOx sensor right away?

No. Check the connector, wiring and power supply first. The sensor is expensive and corrosion or a damaged wire is often the real cause.

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.