Many 850 owners have reported PNP switch failures in cold weather. I recently had mine replaced at 93000 miles. Each winter it set the trouble code a couple of times, but this became too frequent to put up with.

I got back the old switch and opened it up to see if I could tell why it failed. I think other switches and sensors on cars (like throttle position sensors, A/C compressor clutches, etc.) are also exposed to weather and get much more use (especially on the highway), but usually last much longer.

The moveable contacts on the PNP switch were somewhat worn but mainly the entire switch was full of grease, which had spread all over the contact surfaces. It doesn't look like this switch is really sealed in any way, and in any case it seems odd to design a part where grease can migrate all over electrical contacts. I would think ice could also form inside.

Has anyone else looked inside a PNP switch or investigated why they fail?

Thanks,

ksg