Help for Liebherr F2 fault please

Good evening

Realised I might be more likely to get a response if I post this query as a new topic (rather than as an add on to an existing similar post as I did earlier today)
New on here, so please bear with me.

I have Liebherr Fridge (Model KBES 3650-21B / 147, service no 0976712-02), also displaying F2 fault and beeping intermittently

I have read previous replies to this fault code query and know there should be 3 sensors but just want to check whether it is just the evaporator(?) sensor (located at the bottom of the back panel beneath the polystyrene board??)) that needs replacing or do i need to replace all 3 sensors?

I think I have located one other sensor (the air sensor??) behind an integrated grill on the back panel (but accessible only by removing the polystyrene panel from behind it) but cannot find the other. I have checked by the light housing and the fan.

I can post photos if it helps.

Any help greatly appreciated thanks.