My Oil Pressure gauge has been "stuck" at 3 bar for about six months now. Sort of a curious problem. When the engine is off but the ignition is set to position "2"(on) , the gauge will read zero, as it should. When you start the car, the gauge has about a half second delay and then shoots to the top of the scale and stays there until the car is turned off.
I've read that this is a classic indication of the oil pressure switch is bad. Well I finally got around to ordering the replacement switch. Put it in with relative ease. Only problem is the this didn't cure the problem.

A couple of notes: The old switch would allow the needle to move ever so slightly -maybe 3.0 to 3.1 bar as the engine reved up from idle. The new switch makes the needle stick to the top (approx. 3.1 bar) with no needle waver at all.
I cross referenced the part numbers and the new part matches the old one. (004-542-94-17)
I get about 81 ohms on the old switch sitting on the bench.

Could my pressure really be that high?? At idle??


cc: benzworld.org

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Paul Hansen

1997 S500 (100,000mi)