Engine Oil Fill Level Sensor, Basic Function - GF18.40-P-2001A

Engine All (4xWD) 

Engine All (CAR) 

Sample diagram with engine 282 

Courtesy of MERCEDES-BENZ USA

Overview 

This document contains information on:

• General 
• Function requirements 
• Function 

General 

The engine oil fill level sensor (1) measures the distance between the sensor on the oil pan floor and the oil surface using ultrasound and thus continuously determines the engine oil fill level.

Function requirements 

• Engine in operation.

Function 

A piezo ceramic emits an ultrasound signal. The sound moves upward in the measuring tube system: it is then reflected in the oil surface, moves back downward and is detected by a sensor next to the piezo ceramic. The sensor measures the time between sending out and receiving the ultrasound and calculates the distance to the surface from this. As the temperature has an influence on the sound velocity the oil temperature at the oil sump is measured by a sensor integrated in the engine oil fill level sensor (1) and taken into account in the run time calculation. The information on the oil level and oil temperature is transmitted by means of a digital signal to the powertrain control unit for evaluation and further processing.

The oil inlet to the measuring tube system is separated by a meander structure, a labyrinthine structure, from the oil pan. This structure prevents the intake of oil foam into the measure system, which impairs the measurement.

This measurement is repeated continually so that the oil level can be determined even in the case of a sporty driving profile. Depending on the driving profile, the lateral and longitudinal accelerations affect the measurement.

The engine oil level is determined during ongoing driving operation. In the case of a normal driving style, the determination of the engine oil level can take up to 30 minutes, in the case of an agile driving style, it can take longer.

	Component descriptions
	Engine oil fill level sensor component description	Model 223	GF18.40-P-4117A
		Model 206	GF18.40-P-4117C
		Model 254	GF18.40-P-4117H
		Model 464	GF18.40-P-4117J
		Model 214	GF18.40-P-4117K
		Model 118 as of model year 2023 Model 177, 247 as of model year 2022	GF18.40-P-4117L
		Model 167 as of model year 2023	GF18.40-P-4117M
		Model 192	GF18.40-P-4117R
		Model 236	GF18.40-P-4117S