Code 23B Intake Air Temperature (IAT) Sensor Circuit

HIGH TEMPERATURE INDICATED




Circuit Description
The Intake Air Temperature (IAT) Sensor uses a Thermistor to control the signal voltage to the Engine Control Module (ECM). The ECM applies a voltage (4-6 volts) to BLU/BLK wire of the Sensor. When Manifold air is cold, the Sensor (Thermistor) resistance is high, therefore, the ECM will see a IAT signal. As the air warms, the Sensor resistance becomes less and the IAT signal drops.




Test Description (IAT High)
Number(s) below refer to circled number(s) on the diagnostic chart.

1. This check determines if the Diagnostic Trouble Code (DTC) 23B is the result of a hard failure or an intermittent condition. A DTC 23B will set if:
- Engine has been running for longer than 3 minutes.
- An IAT greater than 150°C is detected.

Diagnostic Aids
- If the Engine has been allowed to cool to an ambient temperature (overnight), Engine Coolant and IAT may be checked with a "Scan Tool" and should read nearly the same.
- A DTC 23B will result if BLU/BLK or BLK/WHT wires become open.
- If DTC 23B is intermittent, refer to Diagnosis by Symptom. Symptom Related Diagnostic Procedures