W220 Faulty Boot Lock

Bertie Wooster

Senior Member
Apr 28, 2016
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Your Mercedes
W220 S320cdi
Evening chaps. I hope all are well and surviving these crazy days.

So, my W220 S320 (05 facelift) seems to have developed a very annoying fault. When you unlock the boot, either using the drivers door switch, the key fob, or the button on the boot lip itself, it does the following:

Unlock boot,
Boot pops open, courtesy handle pops out,
The latch immediately shuts to the locked position, boot light goes off.
Boot won’t (obviously!) lock when you close it.

For now I’ve managed to work out a cheat to allow the boot to be closed, by sort of blipping then lock and very quickly shutting the boot in the second or so that the latch is in the right position.
If it helps, I can hear a very obvious hiss of air (vacuum leak?) when the lock actuates.

Any thoughts? Is this something worth me stripping down, or does it need a STAR session to diagnose?

Best to all!


Senior Member
Aug 25, 2006
Reaction score
Midlands / Charente-Maritime
Your Mercedes
'93 500SL-32, '01 W210 Estate E240 (RIP), 02 R230 SL500, 04 Smart Roadster Coupe, 11 R350CDi
Star will likely not tell you much.
I'd be pulling the lining off and checking the latch and pipework.

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