Old PIR issue

I have an old outdoor PIR that was installed back in 2000. The PIR is on my deck so has been under cover all it's life.

It is configured to come on at night only for about 10 minutes. For some reason however of late it more or less constantly triggers. If turned off manually withing seconds it is on again despite there being nothing to warrant triggering it. I have home minder and have been logging every time it comes on, so get log full most nights. Oddly about 1 in 3 nights it doesn't come on at all which is what I would expect.

So any idea of why? Do these things 'go bad' with age by any chance?

 

The first thing to check is that nothing thermal has changed in it's vicinity recently. Make sure that a bathroom external exhaust vent hasn't been fitted nearby, for example.

The most common causes of sensors going bad are moisture and "wildlife". Since it's over 10 years old and misbehaving you've got nothing to lose by taking a look at it yourself. Check things like evidence of moisture coming down the cable, a split or loss of seal around the lens, a crack in the housing, a missing screw, spider making a nest inside, etc.

Something else to try is increasing the Time Threshold parameter on the Global tab in toolkit from 96ms up to 208ms. This will increase the sensor immunity to rapid transients, at the price of a little sensitivity.

 

Thanks for that, had a bit of a look at it last night and no signs of any physical issue. I changed the time threshold as suggested and last night was one of the most 'quiet' nights it has had in a long while. It came on just twice (suspect cats) which is about what it was doing before. Will see how it goes over the next week or so.