Intake Air Temperature Sensor

Cold air is denser than warm air, so it contains more oxygen per litre. The control unit uses the intake air temperature to correct fuelling and ignition timing. On many cars the sensor is built into the mass air flow sensor. Turbocharged engines often have a second sensor after the intercooler to measure charge air temperature.

On many cars the sensor is built into the mass air flow sensor housing. Turbocharged engines often have another sensor after the intercooler. Cold air is denser and contains more oxygen than warm air, so the control unit uses the intake temperature to correct its air mass calculation, ignition timing and, on turbo engines, boost. On hot days or after a long idle, intake temperatures can rise well above the outside temperature, which slightly reduces performance.

Like the coolant sensor, it is usually a thermistor whose resistance changes with temperature. Like a coolant temperature sensor, it is usually a thermistor whose resistance changes with temperature.

A faulty sensor or wiring causes codes such as P0113 and can lead to poor running or hard starting. An implausible reading can make the engine run rich or lean. A false reading can affect fuel mixture and ignition timing, causing poor running or higher consumption. Compare its live value with outside temperature on a cold engine.