So today I thought it was overdue time to check the sunroof drains on my 2015 L405. I have seen some horror stories of these rusting out and then causing huge damage to the interior, so I was more than a little nervous taking off the trim panels to expose the drains.

Luckily, although there was some crud, the drains were not blocked and cleaning the area down the water ran away freely. I poured about 2 litres of water into the channels to flush them out and the water all drained easily.

On drying it all off (I used my car blower/dryer) I found only the slightest trace of rust around the drains. I used Kurust to treat this minor surface rust and then Lanoguard to seal and coat the drain tube area.

I feel lucky that I didn’t discover a horror story today, but would encourage others to check/clean/wax the drains on their L405. It’s an easy job to pop the trim panels off and check.

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Also the sleeve insert could be of help:

https://www.fullfatrr.com/forum/topic74149.html

Worth noting that you can see the drain holes without risking the trim removal. Use a ladder, and look back along the channel when the roof is open.
Use adapted tools to clean out any muddy paste.
Using strimmer line, or the tool for the job with the pipe brush, it's easy enough.
Flush through with a Milton solution and watch for the fluid exit near rear mudflap. L405 2014 FFRR Autobiography
Corris Grey
Previously 2011 D4 SDV6 HSE Santorini

I think for future maintenance that is the way to go, but I wanted to get a proper look at them (and I was expecting to have to do some remedial work to them) this time as I had never inspected/cleaned them before.

Any advice for trim removal please?

Open the sunroof and starting from the front of the car, grab the trim from the inside and pull, there are four clips in total.

These are the clips that hold on the aluminium trim rail

Click image to enlarge

Bardley wrote:

Worth noting that you can see the drain holes without risking the trim removal. Use a ladder, and look back along the channel when the roof is open.
Use adapted tools to clean out any muddy paste.
Using strimmer line, or the tool for the job with the pipe brush, it's easy enough.
Flush through with a Milton solution and watch for the fluid exit near rear mudflap.

Both sides exit at the top of the rear wheel arches. If you have water exiting to the front then this suggests that the drain is blocked.

See below - drains are marked as 4 and 6