Oil Level Sensor: Description and Operation

GF18.40-P-4114P Component Description Of Oil Level Check Switch
ENGINE 642 in MODEL 164.1 /8, 203.0 /2, 221.0 /1, 251.0 /1 up to Model Year 2008 /AEJ 07
ENGINE 642 in MODEL 209.3 /4, 211.0 /2 /6, 219.3
ENGINE 642 in MODEL 463 up to 31.5.12





S43 Oil level check switch

Location
The oil level check switch is located on the underside of the engine and is fastened with the base plate on the inside on the large oil pan. The jack on the oil level check switch is located on the output side at the bottom left.

Task
The oil level check switch has the task of recording the oil level and forwarding this over a discrete line to the CDI control unit (N3/9).





Body
Shown on engine oil level greater than "Min"

30 Float
31 Ring magnet
32 Reed contact
34 Ground contact
39 Baseplate
41 Housing

S43 Oil level check switch

Function
The engine oil levels in the oil level check switch and oil pan balance out over the feed and drain bore. The float is moved according to the oil level. The reed contact is opened at an engine oil level of less than "Min" and closed for an engine oil level of greater than "Min" by the magnetic field of the ring magnets.
If the dry-reed contact is opened, the connection to ground contact is interrupted and a warning message appears in the multifunction display (A1p13) in the Instrument cluster (A1) concerning an unacceptably low oil level.

The volume of the housing and size of the drain bore on the oil level check switch compensate for short-term level fluctuations and thus unnecessary warning messages. Level fluctuations can occur, for example, during cornering.