CL500 2007 Alarm keeps going off

[Mickcedes]

HI guys, any ideas ? 20 secs after locking doors alarm goes off. It is a keyless go 2007 C216 CL500. I have to leave car unlocked over night to stop it !!!!!!

 

[KillerHERTZ]

Alarm battery on its way out. Located in front wheel arch (wheel off job) and it comes as a complete unit - around £100. You will need a security torx bit to replace it.

 

[optimusprime]

First before going and purchasing a new battery unit at £100 take a look at the alarm switches on the boot and bonnet for corrosion . There may be some on the doors also.

 

[Dord1954]

Hi my alarm failed a couple of weeks ago although symptoms did not point to the siren (I had no sat nav or radio signal all fed from the same fuse as the alarm) I assume that the indicators flash at the same time as the alarm sounding so if you just disconnect the alarm and the lights dont flash after locking the car then I guess it is the siren that is at fault and being as your car is 10 years old (similar age to mine) its a pretty safe bet.
the siren is quite easy to get at behind the front nearside wheel arch, I think I have a link to instructions somewhere

 

[Dord1954]

here is the link, well within even a novice mechanics ability as I found out
Mercedes W211 E Class W219 CLS Alarm Siren Replacement ? infinity squared

 

[Mickcedes]

Alarm battery on its way out. Located in front wheel arch (wheel off job) and it comes as a complete unit - around £100. You will need a security torx bit to replace it.

Thanks for info, Ive had consumer battery checked and apparently its been drained quite heavily and just needs a full charge. fingers crossed