Today my low collant level dash light came on my '92 2.5. There is plenty of radiator fluid in the resovoir. What is the deal?

It could be a bad sensor. Mine had a bad coolant reservoir cap and ended up losing pressure and leaking, causing the light to come on.

veedubtdi,

Thanks for the input. Although a visual inspection showed no signs of leaking

Try to unplug the wires at the sensor. If the light goes out, it is a bad sensor. You can also use an Ohm meter to measure its resistance to determine if it is bad. But I forgot the numbers. I faintly remember that it should close (zero Ohm) when coolant level is low and open (infinite Ohm) when coolant level is high. Do not quote me on this as I di dthis a while ago. The factory manuls have the numbers.

The sensor is easy to replace and inexpensive. About $15.

Get a radiator shop (or good mechanic) to check your pressure cap. It's a bit early for it to fail, but if it won't hold pressure, you will get boiling in the head and bubbles in the coolant tank, which the sensor will 'see' as low coolant. When the car cools off, the boiling stops and the coolant light goes out.

I'm presuming it came on, then was off later -- if it is on and there is sufficient coolant present (open the pressure cap and look in -- engine cold, please!), the sensor is shot. Coolant should come up to the "seam" between top and side of tank, no lower.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!