Eclass sensora

[.richard]

Bought 2013 E class four weeks ago. Had tow bar fitted after two days. Can't fault delivery of vehicle and how tow bar was fitted. However sensors front and rear occasionally fail. Sometimes one or other. Lights appear to say live but then don't work. Could be sensors or fitting of towing electrics. Why should front sensors go off with tow ball electrics? Two minutes later the car performs perfectly. Any ideas? Car booked into MC under warranty but I think it may be linked to tow electrics. Someone mentioned a series circuit, but why does that affect the front? Did the car have this problem before I got it? Help would be appreciated.