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Premium Member 2001 SLK320/2000 SLK230
2,719 Posts
Discussion Starter #3
Oh ye of little faith. See here.

"The three-valve per cylinder (Mercedes) V-6 engine, which also appears on the midsize C280 sedan, is equipped with a special dielectric sensor in the oil pan that measures the amount and type of contaminants in the oil, as well as how the vehicle is being driven."

Now that I have the reading, I am trying to find out how to interpret it. (see pic).

BTW the Autel people seem much more responsive to questions than the iCarSoft. Ordered a DiagLink which should be here tomorrow and will see if that has more information.


Super Moderator CA 2012 SLK55 AMG w/P30
13,843 Posts
Measures capacitance of the oil:

Oil quality is determined by the electrical capacitance of the engine oil (engine oil can store an electrical charge). The charge level increases as the oil quality deteriorates. By measuring that capacity, the engine control unit (ECU) can determine the quality of the oil
In addition, Daimler discovered that oil degradation is correlated directly with its ability to conduct electric current. Therefore, Daimler has fitted V-6 and V-8 engines with a digital oil quality dielectric sensor, that is mounted above the oil pan along with an analog oil level sensor. This sensor measures changes in capacitance, which effectively is a proxy for the amount and type of contaminants and oil degradation products present in the oil. An increase in dielectric constant (less resistance to electrical flow) indicates oil contamination and degradation.

Daimler-Benz (Mercedes-Benz) has been incorporating the sensor into its vehicles since 1998.
I'm getting closer to your question but no cigar yet.

That's one of the reasons I'm not getting a scanner/reader: you need to know what the values are supposed to be. I've no idea what a particular "reading" means so knowing it won't do me any good. Need some kind of manual that says "xxx voltage range is 'xx' to 'yy' for example.

For example I've found:

These are the signal assignments from the oil sensor:

On/off ratio signals OK
A: Oil temperature 20 to 80%
B: Oil level 20 to 80%
C: Oil quality 20 to 80%

On/off ratio signals is greater than 80%
A: Oil temperature is greater than +160°C
B: Oil level is greater than 80 mm
C: Oil quality good

On/off ratio signals is less than 20%
A: Oil temperature is less than -40°C
B: Oil level is less than 0 mm
C: Oil quality poor
Depending on what the sensor reads, the idiot light comes up on the dash.

In answer to your question, pending a positive result, since you have a current reading right now, measure it before and after your next oil change.

At least you will then have a base figure to refer to and then over time, measure it and record. Maybe you can infer what that number means.
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