Oil Level Sensor: Description and Operation

GF18.40-P-4114MAR Component Description Of Oil Level Check Switch
ENGINE 156.981 in MODEL 230.470 as of Model Year 09 /Modification Year 08 model refinement package





View of oil pan top section

1 Oil pan top section

S43 Oil level check switch

Location
The oil level check switch is located at the rear front in the oil pan top section.
The connector for the oil level check switch is located at the rear right, below the oil pan top section.

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.