Coolent warning light and sensor, easy to replace sensor

[MingeBlue]

My Coolent warning light has started randomly comming on when I start from cold, the coolent level is fine, also noticed its struggling a bit to start from cold.

I did a bit of a google-ing and its points to the Coolent sensor being faulty which is a common fault, I noticed some people mentioned replacing the sensor and header tank, do you really need to replace both ? Is it as easy or easier to replace the coolent sensor compared to the temp sender ? I ask because I did the temp sender a year ago and I managed that ok

 

[Welly]

Yep, new header tank as far as I know - it's moulded in.

A couple of bolts and two pipes - not hard.