Oil Level Sensor: Description and Operation

GF18.40-P-4114MIR Component Description Of Oil Level Check Switch
ENGINE 272.949 in MODEL 230.454 as of Model Year 09 /Modification Year 08 model refinement package
ENGINE 272.968 in MODEL 230.458 as of Model Year 09 /Modification Year 08 model refinement package
ENGINE 273.965 in MODEL 230.471 as of Model Year 09 /Modification Year 08 model refinement package








View of the engine oil pan

S43 Oil level check switch
Arrow: Plug connection

Location
The switch is located in and the connector is located outside on the engine oil pan.

Task
The oil level check switch recognizes the minimum oil level in the engine oil pan.





Body
Shown with sufficient engine oil level

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

S43 Oil level check switch

Function
The engine oil from the engine oil pan reaches the switch via 2 bore holes in the switch housing. The float moves according to the oil level. The dry-reed contact is closed for an adequate engine oil level by the magnetic field from ring magnets. If the engine oil level becomes too low the dry-reed contact opens and the connection to the ground contact is interrupted. This recognized by the ME-SFI [ME] control unit (N3/10) and a suitable warning signal is sent via the engine compartment CAN to the instrument cluster (A1).

Short term fluctuations in the level are balanced out by the size of the oil volume and the 2 holes the switch housing (for example when braking or cornering) which prevents unnecessary warning signals.