My car has been sitting outside since the end of October and I just started it up today. No problem to start as it had been on the C-Tek. Ran like a dream as usual but it started to make some odd noises which I eventually tracked to the stereo.

There was a crackling noise from the front off side tweeter, then a similar crackling from the centre dash speaker and a deep boomy noise form the rear nearside. All are intermittent and the music, via the radio, seems normal.

I've also had a couple of minor alarm issues as in; went to the curry house for a take-away, locked the car and within a couple of minutes the hazzards were flashing and the alarm was sounding.

I'm guessing I've probably got water ingress somewhere, maybe just condensation. Whenever I open the rear doors after a long standstill I get water coming out for a couple of seconds and the inside windows tend to mist up until the air is on them.

Where should I check for possible issues? 2017 5.0 Autobiography Supercharged
2005 Merc SL350
2005 Disco HSE 2.7 oil burner

Rear left cubby - that is where all the infotainment gizmos live

Also, the LCM (behind the A pillar cover where the bonnet release is). A night in the airing cupboard might work wonders  .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

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Thanks Joe.

A couple of runs, with lots of heater action and the rear left cubby cover off and the back seat down and all is back to normal. Obviously it was feeling neglected, or maybe a little damp. There's a little old rust on top of the SATNAV unit but no sign of recent water ingress so it appears the damp from poor weather lately was the problem.

Now the inside of the sunroof needs to dry of condensation.

It's a double garage for me next time so the fatty can keep the SL company in the dry. 2017 5.0 Autobiography Supercharged
2005 Merc SL350
2005 Disco HSE 2.7 oil burner