The intake air temperature sensor is integrated in the air mass flow meter. In this way, the intake air temperature is measured at the same point as the air mass flow. A precision NTC resistor is used to convert the ”temperature” into a measured ”resistance” level which can be evaluated electrically by the DME control unit.
The intake air temperature is used for 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
- Valvetronic control
- Activation of secondary air system
- Activation of electric fan
If a fault occurs on the temperature sensor, a fault is recorded in the DME fault memory. In this case, a fixed programmed substitute value is used for engine operation.
If there is a fault on the air mass flow meter connection, an intake air temperature sensor fault may also be entered in the fault memory.