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P codepowertrainMedium severity

P2224NOx Sensor Heater Sense Circuit High (Bank 2)

The Bank 2 NOx sensor heater sense circuit is stuck at a high voltage, typically from a short to power or a failed sensor feedback circuit.

Definition

The control module monitors a heater sense circuit that reports Bank 2 NOx sensor heater voltage or current so it can verify the element reaches and holds operating temperature. P2224 sets when that feedback signal stays above the plausible maximum, indicating a short to battery voltage, an open circuit floating at pull-up voltage, or a failed feedback stage inside the sensor's integrated module. The module discards Bank 2 NOx data, the MIL illuminates, and the NOx/SCR monitors cannot complete, causing an emissions-test failure and, on diesels, potential progression toward SCR inducement derate.

Common causes

  • Heater sense wire shorted to battery or reference voltage
  • Open sense circuit reading pull-up voltage
  • Failed NOx sensor internal feedback circuitry
  • Heat-damaged harness insulation near the exhaust
  • Corroded connector terminals causing erratic high readings

Common misdiagnoses

  • SCR catalyst
  • DEF injector or pump
  • Bank 1 NOx sensor
  • ECM/PCM replaced without isolating the harness short

Troubleshooting steps

  1. 1.Confirm the code and review companions

    Note whether Bank 2 heater control codes are also present, which shifts suspicion to shared wiring or the sensor module itself.

  2. 2.Test the sense circuit for a short to voltage

    With the sensor disconnected and key on, constant battery voltage on the sense wire confirms a harness short to power.

  3. 3.Check circuit continuity and connector condition

    Verify the feedback wire is continuous end to end and terminals at the sensor module connector are tight and corrosion-free.

  4. 4.Inspect harness routing near heat sources

    Look for melted insulation where the harness passes exhaust components, a common cause of wire-to-wire shorts.

  5. 5.Replace the NOx sensor if wiring is verified

    With a clean harness, the high feedback reading originates in the sensor module; install an OE sensor, clear codes, and confirm monitor completion.

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