Recessed door/window sensors

I have recently had issues my GC2 panel inconsistently recognizing closing of opened wired recessed window and door sensors. Openings always registered on the panel, but closings oftentimes were not. After replacing the couple sensors with this issue, opening and closing both seem to be consistently recognized now.

Are wired recessed sensors known to fail in this way? What is the typical lifespan of these sensors? What is normally the cause of the failure? Is it related at all to the magnet?


Wired sensors don’t typically “fail” so to speak. They are extremely simple.

However, over time smaller issues can be magnified. Misalignment is often a problem, where the magnet and sensor don’t line up properly. This will often get worse over time due to wear and tear on the windows/doors. It might also get worse seasonally, as hot and cold temperatures cause the material to contract/expand.

It is also somewhat common to find magnets have been replaced by a different size/shape of magnet with a different strength. This will affect the magnetic gap distance where the sensor will show closed.

Different sensors have slightly different magnetic gaps. Sensors/wires may also be affected by corrosion.

Ultimately it’s usually not really a matter of lifespan of the sensor itself.

The reed switch side of the contact sensor can and does fail occasionally but usually I don’t see that until they’ve been in service for 15 to 20 years. There were a few bad batches of some cheap ones on Amazon that some folks had trouble with…at an industry association chapter meeting before this COVID stuff an installer was saying he had to replace a slew of them.

I definitely agree with Jason in that the magnets often get misaligned, especially when they were affixed to a window with double sided tape as the glue sometimes lets go a little in season after season of hot weather.

The sensor and magnets cannot become misaligned - they are fixed in place as they reside inside holes drilled into the window and frame. On one of them, I replaced only the sensor initially (set inside the window frame), which decreased but did not completely eliminate the unreliability. I then replaced the magnet (set inside the moving window) as well, which seems to have eliminated the unreliability, so far at least.

The sensor and magnets cannot become misaligned - they are fixed in place as they reside inside holes drilled into the window and frame.

These unfortunately can and do become misaligned (and can unfortunately be installed that way from the start). If installed near the edge of its effective magnetic gap or a little misaligned from the start, even minor wear and tear over the years can affect the sensor’s ability to stay closed. I saw this a lot on older windows when I installed systems reusing existing wired sensors. It was most prominent on 3/8 inch recessed sensors.

When replacing sensors you will generally want to replace the magnet with the one that comes with the sensor. Not all magnets are the same.

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You’re absolutely right. I’ve seen window sensors become misaligned because the building settled a tiny bit such that the window still slides perfectly in the track but the gap between the switch and magnet grew just enough to cause the sensor to open. This can be quite concerning to the homeowner at 3AM, lol.

This is a weird one to be sure. Permanent magnets can be demagnetized but only under extraordinary circumstances…I still wonder if a few of the reed switches are starting to fail. Since Aurora is using a GC2 I’m assuming that the install isn’t that old.

got it. thanks

Yeah it is always possible for a reed switch failure, it is a moving part, just rare in my experience. Replacing the wired sensor and magnet pair is inexpensive and can resolve a few potential issues. If you notice 100% consistency after replacing you should be good to go.