IS300H Alarming for No Reason

[Paul-B]

Last night at about 3am my 2014 IS300H alarm went off for no reason and after about 10 seconds stopped by itself.

I checked CCTV and there was no sign of anything suspicious so unsure what would have caused it and furthermore why the alarm stopped itself after a few seconds. 

Done some research this morning but couldn't find an answer. 

Any ideas what caused this to happen?

[Mincey]

My IS250 did the same thing. It was the only time in 12 years it happened and like you, there were no ne'er do wells loitering around when I went out in my dressing gown to check and nothing on the CCTV either. Maybe it's an attention thing?

[PCM]

38 minutes ago, Paul-B said:

 

Any ideas what caused this to happen?

Wind/rain? Moth? ...

[Paul-B]

6 minutes ago, PCM said:

Wind/rain? Moth? ...

Yeah maybe wind set it off but what I can't understand is how or why the alarm stop by itself after a few seconds 

[Pompeyscouser]

I had this happen to me once when it was a very windy night and it was only in the morning I noticed my boot was unlocked and the wind was lifting it slight with, consequently, the alarm kept going off. I’m sure this might be a red herring but, check your boot!

[Paul-B]

46 minutes ago, Pompeyscouser said:

I had this happen to me once when it was a very windy night and it was only in the morning I noticed my boot was unlocked and the wind was lifting it slight with, consequently, the alarm kept going off. I’m sure this might be a red herring but, check your boot!

Checked the boot and it was closed tight. I don't know what caused it and what made it stop 😕

[paulrnx]

Very windy last night. I wonder if it was enough to rock the car on its suspension sufficient to set off the motion sensor?

[Paul-B]

2 minutes ago, paulrnx said:

Very windy last night. I wonder if it was enough to rock the car on its suspension sufficient to set off the motion sensor?

Yeah that could explain why the alarm went off but what would explain it stopping by itself after a few seconds is what's puzzling me

[paulrnx]

Not sure how the alarm works. You would think it would carry on wouldn’t you.

[ColinBarber]

Are you sure it was only 10 seconds? The alarm is meant to sound for 27.5 seconds before stopping and going back into an armed state.

[200h]

could the 12v Battery trigger the alarm if it where low on charge

[Subtronics]

Probably un-related, but I had an Accord that the alarm kept going off and it was the little push sensor in the door shut. Took it out freed it up with a bit of grease and that sorted it. The car just thought the door was open. Just something else you can check. Just push each one in and see if it moves freely. 

[barryb]

I had a similar thing with my IS200t, alarm was going off then stopped, went out looked around the car and nothing, went in the car and it was a daddy long legs lol!

Once the beast was escorted out the car it was fine, talk about sensitive.

Barry

[BigChange]

We had a similar situation with a previously owned Subaru.  Finally traced to the failing Battery which was replaced and problem stopped.  

[delfinus]

My alarm was triggered one time since I have my car. It was a fly or a wasp locked inside the car. I saw it flying out when I opened the door. After that it was quiet  and no more alarms since then. I would say this alarm system is pretty much sensite for what kind of things are moving inside your locked car :).

best d.