What are these called or where can i get one.
would imagine they're two wire ... placcy/bakerlite body so non conductive .. would need two contacts ...... well found @GeckoFrom your airfilter?
Continuously monitoring engine air filters, the Filter Minder® Non-Locking Air Switch triggers an air filter warning light directly or via engine computer.filterminder.com
From the Donaldson catalogue (page 201)
View attachment 18284
(you'd need to check if they are one wire or two)
True, but the other way to look at it: It tells you you've forgotten to check the filter in waaaay too long!tells you when yer motor's gasping for breath 'cos yer filters clogged