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P codepowertrainMedium severity

P0436Catalyst Temperature Sensor Range/Performance (Bank 2)

The Bank 2 catalyst temperature sensor signal is implausible compared with the exhaust temperature the PCM expects.

Definition

P0436 is a rationality fault for the Bank 2 catalyst temperature sensor: the signal is electrically valid but stuck, slow to respond, or in disagreement with the modeled exhaust temperature, the Bank 1 sensor, or ambient after a cold soak. The PCM stops trusting the reading, suspends Bank 2 catalyst temperature monitoring, and turns on the MIL. Driveability is unaffected, but the vehicle will fail emissions testing, and on diesel applications an inaccurate reading can disturb aftertreatment temperature control.

Common causes

  • Drifted or slow-responding sensor element
  • Soot or carbon coating on the sensor tip
  • Intermittent resistance in the connector or harness
  • Sensor loose in its exhaust boss or not fully seated
  • Exhaust leak near the Bank 2 sensor cooling the gas locally

Common misdiagnoses

  • Bank 2 catalytic converter replaced for a sensor rationality fault
  • Sensor replaced when the connector's intermittent contact is the cause
  • Oxygen sensors replaced based on the catalyst-range code number

Troubleshooting steps

  1. 1.Compare both banks after a cold soak

    Overnight-cold, the Bank 2 catalyst temperature should match Bank 1, ECT, and IAT within about 10 F; a standing offset identifies the drifted sensor.

  2. 2.Graph both bank sensors during warm-up

    The two catalyst temperature traces should rise together; a Bank 2 trace that lags badly or never moves confirms a lazy element.

  3. 3.Wiggle-test the circuit

    Flex the harness and connector while watching live data; abrupt jumps expose intermittent terminals or a damaged splice.

  4. 4.Inspect the sensor tip and seating

    Remove the sensor and look for insulating soot buildup, and confirm it threads fully home so the tip reaches the gas stream.

  5. 5.Check nearby joints for exhaust leaks

    Leaking flanges or clamps upstream of the sensor draw in cool air and skew the local reading against the PCM's model.

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