Identify this mystery device, please.

[Nick F]

Saw this on a boat for sale. It is on the raw water line, exiting the transmission cooler (just visible with the salt encrustation at the right). Does it contain a zinc anode perhaps?

 

[Blissboat]

Temperature sensor would be my guess, but not sure it needs two wires.

 

[Nick F]

Thanks Blissboat - I had not thought of this. Definitely a possibility. One wire appears to be ground (see photo here), and the casing is plastic.

 

[Fish53]

Flow alarm

 

[Nick F]

Further information: It has 3 wires all connected to the same stud (i.e. connected together). All 3 wires terminate on ground connections around the engine block.

I can now only imagine that the device contains a zinc anode. Device housing is plastic.