Diagnostic Aids

If engine is allowed to cool overnight, coolant and IAT sensor values should be close to each other when measured by scan tester. Check sensor for shifted calibration by using sensor TEMPERATURE VS RESISTANCE VALUES table.

Fig 1: Code 38 Schematic (4.0L) IAT Sensor Circuit Open Low Temperature Indicated

Fig 2: Code 38 Diagnostic Flow Chart (4.0L) IAT Sensor Circuit Open Low Temperature Indicated