My SEL 500 has a wet trunk.

I know this is a problem with this car.

The rear parcel shef has suffered some corrosion also.

How do I go about finding the cause / source of this issue?

Thanks in advance.

If the rear parcel shelf has corrosion and the trunk is wet it would look like you have water getting in around the rear window. Time to pull the rear window, get the corrosion fixed, and replace the window seal. Also replace the trunk lid seal as well, it's pretty easy and a common source of leaks.

Matt.

thanks matt

is this a diy job (replacing the window with a new seal) or one best left to the professionals

is there anyother way around other than pulling?

You can probably pull the window yourself but repairing the corrosion might be difficult for a DIYer.

Matt.