C4GP reheater in diesel fuel filter open circuit?

[c4guy]

Was going to get filter replaced today but mechanic says the reheated is open circuit.
One post on another forum says a guy bought a new reheated but this new reheater was also open circuit.
Is there something special about these reheaters, they apparently look like a rectangle any they are £45+vat to replace.
Thank you for your reply.

[RichardW]

Dunno....no fault codes related to it, so I'd ignore it for now - never checked mine, just refitted it when I changed the filter.