BKD engine - intermittent fuel temperature sensor HIGH read out with engine light

So a couple of years back my engine light came on my ex plugged in the read out for it and found a fuel temp sensor high reading on it. Took to the garage and they told me nothing wrong with the wire, to get a new sensor, which I dutifully did. Ex told me off and looked and said the wire needed a bit of ptft tape ....fixed. Passed 2 mot's no sign of the light then suddenly this year it re-appears. Tested again the same warning comes up again. So now I check the wires to see where this infamous ptft tape is and tried checking it for any issues, nothing seemed a miss so I removed it, still couldn't see anything wrong 😕 Perplexed I thought I will take that soon to the mechanics and ask them to just replace the darn sensor cos it's doing my nut in. Light goes off....4 days no light. I think oh goodie it was just being daft again. 

Sadly the light keeps coming on and off. I've checked the wire, fuel, coolant levels etc but cannot see why this maybe occurring intermittently. I wonder if anyone else has anything similar as not many of my car left on the road apparently now 😢 She still runs like a charm and the most reliable car I've ever known my first baby so I don't want to replace her.