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P codepowertrainMedium severity

P2207NOx Sensor Heater Control Circuit High (Bank 1)

The Bank 1 NOx sensor heater control circuit is stuck at a high voltage, typically from a short to power or a failed heater driver.

Definition

The control module regulates the Bank 1 NOx sensor heater with a switched driver and monitors the circuit's voltage state for feedback. P2207 sets when the heater control circuit reads high when it should be pulled low, indicating a short to battery voltage, an open ground side, or a failed driver in the sensor's integrated module. The sensor may overheat or never regulate temperature correctly, producing no usable NOx signal; the MIL illuminates, the NOx/SCR monitors cannot complete, and diesel SCR systems can progress toward inducement derate if the fault persists.

Common causes

  • Heater control wire shorted to battery voltage
  • Failed heater driver inside the NOx sensor module
  • Open circuit on the control (ground-switched) side reading pull-up voltage
  • Melted or chafed harness near the exhaust
  • Corroded connector terminals creating high resistance

Common misdiagnoses

  • SCR catalyst
  • DEF injector
  • ECM/PCM replaced when the short is in the harness
  • Alternator/charging system blamed for the high reading

Troubleshooting steps

  1. 1.Verify the fault is current

    Clear the code and recheck after a key cycle and short run; note whether it returns immediately, which indicates a hard short rather than an intermittent.

  2. 2.Inspect the harness for shorts to power

    Check where the NOx sensor harness routes near exhaust heat shields and other powered circuits for melted or rubbed-through insulation.

  3. 3.Measure voltage on the heater control circuit

    With the connector disconnected and key on, the control circuit should not show constant battery voltage; if it does, isolate the short to voltage in the harness.

  4. 4.Check connector condition and pin drag

    Confirm terminals are tight and corrosion-free at both the sensor module and any intermediate connectors.

  5. 5.Replace the NOx sensor if the harness tests clean

    A failed internal heater driver is common; install an OE sensor, clear codes, and confirm the heater PID shows normal duty and current.

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