1998 SLK worth a look

[LostKiwi]

Locking will likely be the PSE pump. It controls the air pressure for the door and boot locks.
The water could because blocked drain. Open the bonnet and look for standing water in the area in front of the windscreen. Any puddles of water suggests a blocked drain. Drains can often be cleared with flexible curating wire (the stuff used to hang net curtains).

 

[moblies]

Thanks. I can open boot with key
Didn’t realise you push the lock in doh!

But indicators flash when I press lock and unlock interior light comes on but no central locking

 

[V6Matty]

Water in the passenger footwell if from the windscreen drains being blocked and the water backing up and then running into the heater box, afraid it will also flood a few ECUs behind the dash but once dried out you may be okay, the boot may also be similar in that he rear drains are blocked and it's flooded into the boot and rear SAM.
Your door lock Problen may be related to the water but I'm only guessing here so don't worth taking it to an Indy once it's dried out and have code cleared and then see what comes up again,

 

[Chrishazle]

Another alternative for rodding blocked drains is Oregon 4mm cutting line used in large strimmer/brushcutters, I've used that successfully on my 968 and supplied some to other 968 owners. unfortunately I no longer have the reel of it as I recently gave the brushcutter and all associated bits to a mate to see if he could get it going!

 

[Wighty]

Thanks. I can open boot with key
Didn’t realise you push the lock in doh!

But indicators flash when I press lock and unlock interior light comes on but no central locking

Let's have some pics buddy , that's a cracking price

 

[moblies]

Im drying out the carpet with a small heater and see what I find tomorrow.
The central locking pse is about £300 used on eBay so that’s not so good

 

[moblies]

Interestingly if I press the lock switch on the dashboard I hear a funny sound from the boot. Just does it when I press down it’s like quick sigh almost not a buzz like a motor running

 

[LostKiwi]

If you're lucky it will be a vacuum leak at the pump rather than a dead pump.

 

[moblies]

Well I took the central locking pump out all dry in there. Wiggled tg cables and hit the lock button several times and it locked and unlocked. Just need to find the front leak now.
Also removed a ton of wet mud from the rear wheel arches. Paint is flaking and blistering but metal seems solid enough so will get some rust killer on them for now.