Oil Temperature/Level Sensor
The electronic level sensor is located in the engine sump mounted to the engine oil pan.
The probe of the level sensor contains two temperature sensing elements.
- One senses the engine oil temperature.
- The other is heated to 10°C above the temperature of the engine and then is allowed to cool.
The length of time it takes to cool the heated element is how the sensor determines the engine oil level. When the oil level is high it covers a larger portion of the probe submersed in the oil sump. The engine oil around the probe absorbs the heat of the heated element quicker than if the level is low.
The microprocessor in the base of the sensor produces a pulse width modulated signal proportional to the oil level. The pulse width decreases with a decreased level of oil.
The MS S52 control module uses the oil temperature input signal to protect the engine during cold engine the warm-up phase. Based on the oil temperature, the visual warning LEDs in the tachometer will illuminate at cold engine start up and slowly be extinguished as the oil temperature increases.
The oil temp sensor also serves as a vital input for VANOS operation, varying the solenoid control based on oil temperature (reaction time of camshaft movement).
In the event of a fault the engine coolant temperature is used as a substitute value.