There is a heater in the adblu tank, with a control unit. On a 4X4 version, they locate the unit under the offside rear wheel arch! Sounds a good idea!  Not when water gets into it! My battery flattened at 3-01 am due to the shorting which occurred. Brilliant technician, Noel, (AA VWG recovery service) detected it, ordered a new one, (are you ready?)  £300 retail. Fitted in about 20 minutes, but then testing, resetting elecronic facilities & recharging battery etc.

VW used to have a reputaion for good design & engineering. Glad I took out an "All-in" service/warranty.

VW were the ones that said 'If only everything in life was as reliable as a Volkswagen Golf'. 

Well sadly much in life is....

 

They have no good reputation other than spin from them for engineering or even procuring parts from others, not timing chains / tensioners, door / boot seals. DQ200 DSG,s, Water Pumps, haldex electric control panels,  ECU defeat devices or SCR / AdBlue systems. 

You missed the magic CR140 emissions control systems, which allegedly had some oversights in the programming. 😂