Hi everyone
For your information and for anyone that has a T5.1 and is having Ambient Temp sensor issues, coolant level issues or problems with the N/S headlight/sidelight.
Behind the front bumper on the O/S lower (remove the panel if possible where the front fog light sits), there is a 14 pin plug/connector.
Everything listed above on most models passes through this plug (designed to be disconnected when removing the front bumper).
Sadly this area is prone to water and a substantial amount.
This plug will normally become saturated and will cause all the problems mentioned above.
Best solution is to find the plug, split it and empty it out. Replace the plug and pins if corroded or simply clean with electrical cleaner and WD40.
This should solve all your issues with any of the above.
Good luck.