Ford Focus 2000-05

Intake Air Temperature (IAT) Sensor



The Intake Air Temperature (IAT) sensor is a thermistor that changes the resistance in response to the intake air temperature. The IAT senses the intake air temperature and sends that information to the Powertrain Control Module (PCM). The PCM uses this information to calculate the correct amount of fuel injection.

The IAT sensor is mounted in the following locations:

1.8L engines: integrated with the Vane Air Flow (VAF) meter
1.9L engines: threaded into the air cleaner lid
2.0L engines: at the top left front of the engine compartment, on the front of the air cleaner


  1. Disengage the Intake Air Temperature (IAT) sensor electrical connection.
  3. Connect jumper wires from the sensor connector to the wiring harness. This permits the engine to operate normally while you check the sensor.
  5. Connect a Digital Volt Ohmmeter (DVOM) between the sensor terminals.
  7. Measure the voltage or ohms with the engine off and cool, as well as with the engine running and warmed up. Compare the temperature versus voltage or resistance values obtained with those in the chart.
  9. Replace the sensor if the readings are incorrect.
  11. If the reading for a given temperature is about that shown in the table, the IAT sensor is okay.

    Click image to see an enlarged view

    Fig. IAT sensor temperature versus resistance chart-1.8L engines

    Click image to see an enlarged view

    Fig. Probe the terminals of the IAT sensor and measure the voltage or resistance, then compare the readings to the appropriate chart