Have 83' 300SD 617 with what appears to be a failing oil pressure sensor. Does the booted terminal connection pull directly off the sensor electrical stud, or is there a retention clip or other locking mechanism? I've tried to pull the lead off the sensor with moderate force, and it is stuck.

If the connector is like that on my '87 300D Turbo (W124, OM603) there is a hook that is part of the connector. It hooks over a ridge on the oil pressure sender to keep it locked on. I've had good success with just pulling the connector off. Perhaps you are being too "moderate" but I understand your caution.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
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"Oh lord won't you buy me a Mercedes Benz."
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Thanks for posting. From the replacement part photo I see the groove in the post/stud. I've seen other German connectors with a U shaped wire clip with a wide (open, pulled out) position) and narrow (closed, pushed in) position. Pull clip out to release and lift connector off. Seat connector and push the clip in to lock. I don't see an outer edge of a clip to pull on the MB connector. Since you've had luck with brute force, and the post groove edges look rounded, I'll stop overthinking this one and just pull more forcefully. Thanks.