P0112

CIRCUIT DESCRIPTION
The intake air temperature (IAT) sensor is a variable resistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The powertrain control module (PCM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance decreases. With high sensor resistance, the PCM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the IAT signal circuit. If the PCM detects an excessively low IAT signal voltage, indicating a high temperature, DTC P0112 sets.

CONDITIONS FOR RUNNING THE DTC
- DTCs P0117, P0118, P0125, P0502, P0503 are not set.
- The engine run time is more than 5 minutes.
- The vehicle speed sensor (VSS) indicates that vehicle speed is more than 24 km/h (15 mph).

CONDITIONS FOR SETTING THE DTC
The PCM detects that the IAT sensor parameter is more than 128°C (262°F) for more than 6 seconds.

TEST

Steps 1-2:

Steps 3-7:

Steps 8-11: