The intake air temperature sensor is integrated in the hot-film air mass meter. In this way, the intake temperature is measured in the same place as the air mass is measured. A precision NTC resistor is used to convert the ”temperature” into a measurement value ”resistance” which can be evaluated electrically by the DME control unit.
For the S62 with MSS52, the intake air temperature is determined only in the hot-film air mass meter I on the left-hand side of the vehicle.
The intake air temperature is used in a large number of DME functions, e.g.
- Calculation of injection volume for cold start
- Determining the ignition angle (timing)
- Knock control adaptation
- Idle control
- VANOS activation
- Activation of secondary air system
- Activation of electric fan
A corresponding fault code is entered in the DME fault code memory if a fault occurs in the temperature sensor. In this case, a fixed programmed substitute value is used for engine operation.