parking sensors what next

[Brockuk]

on my 2011 C220 estate W204 my rear sensors stopped working red lights on straight away, connected up icarsoft pro showed both outer sensors faulty , replaced with new, no difference do I try now changing the module first or the rear loom first.
No problems with front sensors working fine. Many thanks for any ideas.

 

[PolishGeorge85]

As much as I believe in MB quality regarding parts. I've came across few issues with wiring. Problem is that is very difficult to prove which one is faulty. I would check wiring from sensors all the way to module, specially paying attention anywhere near corners or tighter places.