My car was outside during a heavy rain storm last week and now the electronics are going crazy. The dash board warning lights are lit up and the radio turns off and on.

The dealer (Knauz of Lake Bluff IL USA) thinks water leaked onto the fuse box and other areas and is causing the issues.

The car was parked under a tree with small leaves so I suspect a leaf clogged up a drainage hole.

The dealer says that it's not covered under warranty and that I need to engage my insurance company. They state that it may cost "thousands of dollars" to fix.

Anyone have experience with MB Warranty and water damage?

Thanks for your help! Tom

MB warrenty doesn't cover external sources of damage. you'll have to tell your insurance company what happened, and pay your deductible, the rest should be covered.

Did the dealer confirm the source of the water?

Our old Mustang had an issue similar to what your describing where debris would clog the cowl (fresh air HVAC intake) drain hole, allowing water to overflow through the vents and enter the passenger compartment and affect the passenger footwell fuse panel. I could see the dealer trying to sidestep this claim due to the debris.

However, although it didn't effect our car, there were also TSBs on that car of failed panel joints causing a very similar issue. In a case like that, I would feel MB would owe correction of the issue and any ancillary damage caused by the failure in workmanship.

Thanks for the info. Insurance company will cover repair but not time for diagnosis (I have escalated to mgmt). Dealer should be looking at it tomorrow. Stay tuned.

Same thing happened to me, car was out of warranty. I took apart my fuse box, dried it out and just about got the car back to normal running condition without the dashboard and the nav going crazy. Heated seats, rear sunshade, passenger airbag light stayed temperamental. So I ultimately found a new fuse box (Front SAM) on car-part.com from a wrecked C for about $200 and put it in myself. The car has been running perfect for the last year. The only thing you have to watch out for is getting a SAM that is coded exactly for your car. Coded meaning taken from a C that is optioned exactly like yours. Because my C300 is loaded with every option I had get the SAM from a wrecked C350 to match my car. At first I got one from another C300, put it in and my self-leveling xenons and rear sunshade didn't work. Usually the part sellers will give you the vin of the wrecked car so you can look up the specs/options on that particular car. If you just have heated seats I feel like you should be okay.

Here's an example of what you need to replace:

http://www.ebay.com/itm/MERCEDES-C300-C350-C63-W204-SAM-FUSE-BOX-ASSEMBLY-2049009601-OEM-/181494177851?pt=Motors_Car_Truck_Parts_Accessories&hash=item2a41e5603b&vxp=mtr
Believe it or not all the malfunctions in your car are a result of this module and will be returned to perfect once its replaced.

Replacing with a new SAM would cost a lot more just because a brand new SAM has to be specifically programmed for your car with a STAR computer. Whereas a used one obviously is already programmed.

Great info. Thank you. The dealer put the car in the sun for a day to let it dry and now everything is working fine. They are going to look for any visual cues for water damage. They are also looking for the leak. Thanks again.

Drains were all clear. Dealer still looking for source of leak. They replaced fuse connections as precautionary.

If there is no drainage issue and the leak is not the fault of an external source they should by all means cover your car. Who buys a car you can't drive in the rain as an everyday driver?

Good news, the car is fine. The dealer ran it thru their car wash 3x, and left it out in a couple of rainstorms and no water leaked into the car. There are some very small wads of leaves in various places on the car so we speculate that leaves clogged the sunroof drain which caused water into passenger side. Lesson learned, check your drains especially now that trees may be starting to drop their leaves.