Signal Waveform

Fig 1: Signal Waveform

Courtesy of HYUNDAI MOTOR CO.

The IATS and ECTS signals should be smooth and continuous without any sudden changes. When the engine is cold, the IATS and ECTS signals should look similar, depending on the ambient air temperature. After warm-up the IATS signal should not change significantly, while ECTS signal should drop. This indicates that the normal increase of the engine coolant temperature is larger than the normal increase of the intake air temperature as the engine warms up.