I have a PIR motion detector in the hallway to turn the light on automatically. It's been installed since 2015 and lately it's been failing pretty often - it doesn't detect when I walk by or takes forever to react. Is it normal for these to wear out, or is there something I can do to get it working like it used to?
Don't try opening it or messing with the internal components unless you know what you're doing because you could break something else. After 11 years, the sensor is most likely worn out or the lens has gotten dirty - first try cleaning the detector window really well with a soft, dry cloth, sometimes accumulated dirt blocks infrared detection. If that doesn't work, check that there haven't been any changes in the area (new objects, plants, temperature shifts) because sometimes the environment affects the sensor. If it still doesn't work after cleaning it properly, honestly at this point it's more cost-effective to replace it with a new one than to try fixing it!
After eleven years the sensor is probably still functional, but yeah, PIR sensors do degrade over time. The easiest and most straightforward thing is to thoroughly clean the front lens, which gets filled with hallway dust and that really cuts down on sensitivity. Use a soft cloth or gauze without rubbing too hard. Also check that nothing's changed in the location where it's installed: if there used to be a window and now there's a heavy curtain, or if the radiator's heating more than it did before, that affects the sensor because the PIR detects infrared heat changes, not just movement.
If it's still acting up after cleaning, take a look at the settings. A lot of PIR detectors have a dial or button to increase sensitivity and another one for the delay time, and sometimes they get moved without you noticing or get changed by accident. If the settings are right and the lens is clean, then it's likely the internal component is actually worn out. At that point, it's more cost-effective to replace the whole detector than try to fix it. They're pretty cheap and installation is straightforward if the old one's wired up properly.
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