Hi James, common problem you are experiencing.
I would remove the bumper and buy a new side vent, make sure the panal the vent fits into is nice and straight, apply sealer to the rubber seal on the vent and then push it into place making sure it has clicked into position.
Refit bumper and give the sealer the required amount of time to cured/ set.
Before refiting the interior luggauge compartment trims I would water test the back of the car to make sure its water tight.
I personally wouldnt fit a secondhand pdc unit, I would bite the bullet and get a new one and get any corroded connectors onto the pdc unit replaced at the same time.
Then tie the pdc unit up to the wirng harness in the rear quarter to prevent this from happening again.
Lastly get the dealer to code the new pdc unit.
Hope you get the problem sorted ok

 

Thats great thanks! Do you know what part of the car water will be entering in from so I know where to aim my hose?!?

 

Just use a sprinkler and set it up to simulate rain fall, you want it to land on the back of the car just like if it was raining.

 

That great, I will get onto it on Saturday weather permitting! thanks for your help.

 

One more thing............how easy is the bumper to get off? I have never done anything with cars before but refuse to pay £109+VAT an hour to BMW to do it!

 

What you expect from a Malaysian or BL car tbh pretty shocking stuff.

 

Bumpers pretty easy to get off. Lots of 8mm bolts in wheel arches and underneath.

 

Hi

Is there any guides to check/Remove the bumper and get to the PDC unit?

Thanks

 

Can you get to the PDC unit without taking the bumper off?