2018 RF1-GT 140bhp Mitsubishi CVT Temp guage issue

[antonio1ok]

Hi folks, long time lurker, first time poster! My temp guage has stopped giving me a reading, just dashes, no numbers at the cent/f. When running, keeps heating with no fan kick in, and alarms eventually go off. I've checked relays and fuses, all ok. Was thinking it might be the coolant sensor needs replacing? Had a look with manuals as a ref, still cant find it..... Also, when ignition off, lcd display remains on albeit with no readings, goes off sometimes. Might be that to the left of the lower F reading, it looks like "-L-".....? Fluid levels are good, tried battery off and on but still nowt. Happened pre Christmas, then resolved itself. Now wont resolve. Any guidance would be appreciated :-)