KEEP YOUR COOL
If the temperature gauge reads erratically it’s probably because the thermostat needs to be replaced – a new one costs under a tenner. While cooling systems don’t usually give any problems it’s likely the radiator will have seen better days if the original unit is fitted. On the 620Ti it may be that the engine runs hot because the intercooler is on its limit. The original set-up isn’t quite up to the job and temperature is often towards the upper end.