Circuit Description
The intake air temperature (IAT) sensor is a thermistor that is built into the mass air flow meter. When the IAT sensor is cold, it has a high resistance. The resistance decreases as the temperature of the sensor increases. The ECM continuously monitors the voltage drop across the resistor as it varies with the resistance of the sensor. A low voltage indicates a high temperature and vice-versa. The ECM sets this DTC when the signal from the sensor is lower than expected.
DTC Parameters
DTC P0112 will set when:
| • | IAT greater than 139°C (282°F) |
| • | Engine running longer than 3 minutes |
| • | Engine speed at idle for 10 seconds |
Important: The IAT signal is continuously checked when ignition is On.
P0112 is a (type B) DTC.
Diagnostic Aids
To locate an intermittent problem use scan tool to monitor IAT temperature with Ignition On, Engine Off.
Wiggling wires while monitoring IAT temperature may locate area where short to ground exists.
The IAT temperature may be compared to ECT temperature with a scan tool if the engine has cooled overnight at ambient temperature. They should be within four degrees of each other with ignition On and engine Off.
