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P codepowertrainMedium severity

P2200NOx Sensor Circuit (Bank 1)

There is an electrical or communication fault in the Bank 1 NOx sensor circuit, so the module cannot read oxides-of-nitrogen levels in the exhaust.

Definition

NOx sensors, used on SCR-equipped diesels and some lean-burn gasoline engines, are smart sensor modules that measure NOx concentration and typically report over a CAN data link. P2200 sets when the Bank 1 (usually upstream) sensor circuit is open, shorted, loses power, or the sensor module stops responding. Without a valid NOx signal the system cannot verify or trim reductant dosing, so the MIL illuminates, emissions rise, and on many diesel trucks a persistent fault starts an inducement strategy that progressively derates power or road speed.

Common causes

  • Failed NOx sensor module (heater or sensing element failure is common)
  • Blown fuse or open power feed to the sensor module
  • Damaged or chafed harness between the sensor module and its connector
  • Corroded or moisture-contaminated connector
  • CAN communication wiring fault to the sensor module
  • Sensor tip damage from impact or excessive soot/condensate

Common misdiagnoses

  • SCR catalyst or DEF injector replaced for a sensor circuit fault
  • DEF quality blamed and fluid replaced repeatedly
  • Downstream NOx sensor replaced instead of the Bank 1 upstream unit
  • PCM replaced for a lost sensor power feed

Troubleshooting steps

  1. 1.Identify which sensor position set the code

    Confirm sensor location from service data; P2200-series codes address Bank 1 Sensor 1, while the downstream sensor uses its own code series.

  2. 2.Check the sensor module's power and ground

    Verify battery or switched voltage at the module connector and check the dedicated fuse; many NOx sensors are powered separately from the PCM.

  3. 3.Verify data-link communication

    Confirm the sensor reports on the network (live NOx and status PIDs); a silent module with good power and ground is internally failed.

  4. 4.Inspect harness and connector

    Trace the pigtail from the exhaust-mounted sensing element to the module and connector, looking for heat damage, chafing, and corrosion.

  5. 5.Replace the sensor with the correct part

    Upstream and downstream NOx sensors are calibrated differently and are not interchangeable; install the position-correct unit and torque to spec.

  6. 6.Clear codes and verify readiness

    Run the NOx/SCR monitor drive cycle or scan-tool system test and confirm plausible NOx readings with no reset of the code.

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