130 pd awx coolant temp low

[bk.bas99]

after earlier post I used VCDS to ascertain that coolant temp was slightly low at 83 degrees. Was going to get round to changing stat when the weather warmed up but since then have noticed that there is a slight coolant leak from somewhere (looses a little bit of coolant over 1K miles) and that the temp sensor was changed a few K miles before I bought it.

If there is a leak somehwere would this cause the system to not presurise proberly and if so drop the temp (I vauguely remember something about temp, pressure and Boyles law in Physics or should I just change the thermostat. Could the new temp sensor be faulty and if so would it be giving the ECU a bum steer?