HelloGiveMeABreak wrote: ↑13 Feb 2021, 12:07Really - Aggressive
I can't see anything aggressive in my post to be honest, maybe you are being over-sensitive.
I had the same vehicle, a little earlier with front and rear assistance, so know that the test works on my vehicle - although if your car has gone into economy mode, it may not work of course.
As far as water can affect the sensors - yes, I speak from extensive experience on all 3 MK I, MK II and MK III C5s I have owned. Water can get up behind the bumper and if the wiring has become unsecured or is hanging in a certain way, any water can run back down the wire and into the sensor module itself causing the intermittent issues.
With this system, it is all or nothing - if any one sensor goes then the system does not work for safety reasons.
The other possible issue apart from a faulty sensor is that the ECU itself has been knocked, or has a bad connection in the wiring plug, or has had some liquid spilled onto the module that is causing problems, for which this also had that happened to me too after 5 litres of screen wash leaked into the boot floor and got into the ECU. It took several weeks to clean and dry it out.
These are just possible answers - but of course the best thing is to have it diagnosed properly with an appropriate diagnostic tool like Diagbox that will provide a fault code(s) and will help determine the cause.
I have the same symptoms as above so I am reviving the tread again. The error message is parking assistance system failure. The rear screen wash also stopped working a few weeks before the parking assisten gave up. Could this be related? Screen wash on the ECU in the boot?