W203 Alarm going off after locking doors

[Chris Lumsden]

Hi guys,

Looking for any advice with things to check with regards to the wifes car (W203 C180K). The alarm is going off after she locks the doors after about 15 secs. I've told her to switch off the internal motion sensor and also the 'tow truck' movement switch internally before locking up but it is still happening. We've never had any issues prior to this but looking for any ideas for things to check before sending her to the stealers? Unfortunately I'm in Algeria at present so not too handy for me to give more information apart from what she has told me. Am I right in saying that if I get it diagnosed it will detail what sensor is triggering the system? She had just returned from driving through a lot of snow/slush so was also wondering if water had somehow got up into the N/S wheelarch where I believe the sounder unit is located? Any ideas or suggestions much appreciated.

Thanks in advance.

 

[markjay]

Check the under-bonnet switch first.

 

[Chris Lumsden]

I did have the bonnet up a few weeks ago before I came away so will ask her to lift and drop it again to ensure its fully closed. I've told her to double check all doors and switches are clear and free!
Cheers mark.

 

[JOB-BLACK-RAT]

Should also say welcome to the forum Chris, sorry it's cos you have a problem, but this is the best (and free'st) way to resolve them!!

Simon

 

[Justin1600]

Normally due to a faulty Alarm siren, it will come up as a fault code on Star Diagnosis.
It is located under the N/S/F inner wheel arch, and the new one will need to coded with Star aswell

 

[MOCAŠ]

I had a similar same problem last night. Heard the alarm going off, went out to check the car - nothing amiss. Unlocked it, and opened and closed both doors in case the windows had not sealed properly. Set the alarm again and went back indoors.

About 10 minutes later it went off again. Went out again, had a good look round, started the engine to check whether the battery had lost voltage. Again, all seemed fine. Set the alarm, went back inside.

You've guessed: a few minutes later it was going off again. I was ready to book it in at the dealership on Monday, but if only to give my neighbours a break I decided to take it for a little run. About five minutes in, something caught my eye at the top of the windscreen. I'd found the culprit: a hoverfly(?). Opened the window, and after taking a tour of the cabin the "hoverfly" eventually flew off.

Problem solved. Hope yours is as simple.

 

[Chris Lumsden]

Thanks guys, problem still unresolved so my mate may have access to diagnostics via his friend so will try to get it checked out to confirm asap