Are you saying the gauge control unit failure was responsible for the starting issue..?
Does the sensor tell the gauge, only then the ECU? That seems unlikely somehow...
This is from memory of what was recounted to me by Roberto Grimaldi at Grimaldi's so I can't vouch for it's accuracy.
The signal from the engine temperature sensor goes to the Gauge Controller, either directly or communicated via CAN from the main ECU. The Gauge Controller was not driving the temperature gauge correctly. The radiator fan was getting a signal (either from the ECU or the gauge controller, can't remember) to turn the fan on full, even if the engine was cold and it was freezing outside. It is probably a safety thing in case of a dodgy temperature sensor.
The ECU relies on getting an accurate engine temperature and if it is reading cold when it is in fact warm the car will be over-fueled, which was exactly the symptom I was experiencing. On warm starts there was a very strong smell of petrol.
I had this intermittent warm-start fault for about 2 to 3 years. The car is a daily driver and it would happen 2 or 3 times a month. Bill McGrath tried to fix it, Grimaldi's and Lancaster's each tried twice and none were successful. I decided to put up with it and plan journeys minimising the chance of a restart being required.
After a while, the fault to the temperature gauge appeared, so I got Roberto to have another look. He originally thought it was the thermostat, so he changed it but the gauge still didn't register the engine temperature properly. That's when he substituted the gauge controller and the car has been fine ever since.