When I came home today around 2pm, the alarm was going off on my 2000 Honda Civic. I turned the alarm off and after a few minutes it went off again. this happened a few more times, till I decided to move the car from the busy main street in front of my apartment building, to a quite gravel parking lot behind the building. So far it's been about 25 or 30 minutes and it hasn't gone off.

I was googleing around and ran across this explanation for a different car:

The most common reason for alarm falses with heat is the hood switch. The expansion of the hood can trigger the pin switch to activate. You can try adjusting it or disconnecting it and see if it fixes it. My E46 also had this problem, but I never got a chance to fix it.

I was wondering if anyone had heard of this type of thing in general? I was thinking that maybe the vibrations caused by passing cars, plus heat expansion at the hood might be why it was going off on the main street, but not parked in back?

Although I doubt it's relevant, I had the engine replaced two days ago.

EDIT July 28, 2016

OK, so at this point I'm sure what's causing the problem. It happens only during the middle of the day when it's hottest out and the car is parked on the main street. It seems the alarm at that time is being set off when city buses go by. I was sitting in the car as one went by and I could feel the whole car shake.

So I guess the question is how can I reduce the sensor's sensitivity a bit so it's not set off when the city buses go by.

2 Answers 2


Although I doubt it's relevant, I had the engine replaced two days ago.

That may well be relevant. On many cars that hood would need to be removed to replace the engine and it is quite possible that this would effect the adjustment of the hood switch. If this is new behavior – if you had no or few false alarms like this before replacing the engine – it seems quite likely that the false alarms could be related to the engine replacement and the hood switch seems like good place to start looking.

  • I was there in the middle of the work and they raised the car on a lift and dropped the engine out the bottom, so I assume they didn't need to do anything with the hood. Jul 20, 2016 at 13:55
  • Still it's the most recent work...
    – dlu
    Jul 20, 2016 at 14:13

If your car has a vibration sensor, you can typically set the sensitivity. You can test this by bumping into your car or trying to rock it a bit.

  • It seems to go off during the middle of the day, whenever a city bus goes by, which causes the whole car to vibrate. Any idea how to reduce the vibration sensor sensitivity a little, but not too much? Aug 9, 2016 at 5:47
  • Googling around a bit, finding some similar issues on forums. Sounds like there should be a black or blue box under your dash. It should have a dial with a knob or slot for a screwdriver. It should be near the main alarm module.
    – rpmerf
    Aug 10, 2016 at 14:47

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