Circuit/System Description
The intake air temperature (IAT) sensor is a variable resistor that measures the temperature of the air entering the engine. The IAT sensor has a signal circuit and a low reference circuit. The engine control module (ECM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit.
The following table illustrates the difference between temperature, resistance, and voltage:
DTC P1111 or P1112
| IAT | IAT Resistance | IAT Signal Voltage |
|---|---|---|
| Cold | High | High |
| Warm | Low | Low |