Rover 200 & 400 Owners Club

they are both coolant temp sensors. One feeds the gauge on the dash.
One feeds the ECU the coolant temp. You have checked/changed the ECU one haven't you as the gauge one doesn't do a lot apart from make the needle go up and down!

maff99 wrote:its on the engine matethere are two plugs on the t piece there one is the coolant temp sensor im not sure wat the other is

The one with a single wire is for the temp gauge, the one with two wires in a multiplug is for the ECU. For the sake of about £10 inc P&P from a Rover specialist it's worth replacing anyway.