The coolant sensor (located between the engine block and the "S" shaped coolant hose connected to the right topside of the radiator) on my 1987 300D (OM603) must have been changed by the previous owner. The sensor only has one two-prong connector on it. My friend has the same car and his coolant sensor has a two-prong and single-prong connector.

The single-prong connector wire is tangling unused. My questions is this: What is the purpose of the single-prong connector and is it worth replacement of the sensor? I have access to a parts car and I may be able to scavenge a replacement sensor. The car seems to run OK, but occassionally will stall at low speeds and sometimes has trouble starting in the morning. Any advice is appreciated.

Regards,
Devin

bump

Do a search on temp sensor posts by gsxr. IIRC the two prong connector is for the Klima relay (cuts the AC compressor when coolant is too hot) and the single connector is for the EDS (controls EGR and ARV, doesn't really affect how the engine runs).

Sixto
... stay tuned

If the sensor is blue, then the 2 prongs are what controls the aux fan. I know this because the previous owner of my car put a wire between these 2 prongs so that the aux fan stays on all the time. Without the wire the fan doesn't come on at all, even after I changed the sensor. I don't know what the single prong does. New sensors only cost $17 at ***************.

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87 300D - Running on Veggie oil; 260,000 plus miles; Original #14 head