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Presence sensor false triggers

Updated: 23 October 2026

The light stays on an empty living room, or it drops while you are still on the sofa with a book. Presence sensor false triggers are those two opposite faults, not one tip list. Name which one you have before you touch sensitivity. The ten indoor rows on the [presence detector comparison](/hub/electronic-surveillance/presence-detector) are radar and hybrid sensors sold to hold occupied while you sit. This page is the fault path after pairing. Placement on a happy path belongs on [how to set up a presence sensor](/hub/electronic-surveillance/presence-detector/sub/presence-detector-how-to-set-up). Peter F., editor for DIY & tools, did not install these units. A qualifying purchase can earn a commission at no extra cost to you.

The light stays on an empty living room, or it drops while you are still on the sofa with a book. Presence sensor false triggers are those two opposite faults, not one tip list.

Our top picks

SONOFF SONOFF SNZB-06P24

Best overall

SONOFF SONOFF SNZB-06P24
8.1/10about £21.85
View offer
Meross Meross MS600

Best value

Meross Meross MS600
6.6/10about £29.99
View offer
SONOFF SONOFF SNZB-06P

Alternative

SONOFF SONOFF SNZB-06P
6.7/10about £24.96
View offer
On this page
  1. 1.Stuck occupied or stuck clear
  2. 2.Fans, curtains, and the cable
  3. 3.The next room
  4. 4.Pets
  5. 5.When tuning is the wrong job

Stuck occupied or stuck clear

If the room is empty and the app still says occupied, you have false presence. If you are on the chair and it says clear, you have false vacancy. SNZB-06P reviews include both. Treating both as too sensitive sends you opposite ways. From firmware 1.0.5, Zigbee2MQTT’s minimum on the SNZB-06P is about 15 seconds. Older builds risk staying present under 30 seconds. Lengthen the lamp delay only if the sensor itself goes clear after you leave. Sitting too still clears an MS605 in one review, and an SNZB-06P24 under about two metres in others. Cutting sensitivity to stop a fan makes that worse.

Fans, curtains, and the cable

A fan, a curtain, a plant, or a lead that twists the aim can hold occupied for hours. The SNZB-06P manual says to keep those out of the zone. On the SNZB-06P24, calibration has failed to remove a fan. The eMotion Pro mount is called flimsy, and a droop toward the hall recreates the fault. Mirrors bounce the beam: one stuck SNZB-06P cleared after it was aimed away from a bathroom mirror. Move the object or the aim before you buy a second unit.
SONOFF SONOFF SNZB-06P24

Testsieger

SONOFF SONOFF SNZB-06P24
8.1/10about £21.85
View offer

The next room

Radar can pierce glass, wood and plasterboard. A UK review describes plants beyond a wooden wall holding an SNZB-06P occupied, and an eMotion Pro has picked up a hallway through an L-shaped bathroom. Shorten the range and point the sensor at the seat, not through the door. Zigbee2MQTT maps SNZB-06P sensitivity to roughly 2.5 m, 3.5 m and 4 m. Those figures are for that model. A higher frequency does not erase this. A hall versus a sofa is the presence sensor vs PIR page.

Pets

The MS600 lists a pet shield, and one UK review says dogs were ignored. That is one report. SONOFF’s SNZB-06P24 FAQ says the sensor cannot filter pets; aim above them. A dog in the beam is false presence if the light must ignore the animal. Do not write an ignores-all-pets line into an automation. On a battery row, every extra occupied minute keeps the radio awake. If the only problem is a pet in a hall you walk through, a PIR may be quieter. Once radar is the right tool, use the best presence sensor page.

When tuning is the wrong job

Aiming into a neighbour’s room, or a tenant’s flat you are not meant to watch, is not a calibration job. The ICO’s home CCTV note is about cameras. A radar with no images is still the wrong tool for someone else’s room. Shorten the range or take the unit down. The SNZB-06P24 10-second reset clears Zigbee pairing. It does not promise that every stuck Detected state will clear. If the fault started when the fan or the mount moved, re-aim before you return the box. If it never paired, that is setup, not a false trigger.

Common questions

Why does the room stay occupied after I leave?
The sensor still sees movement or a reflection in its zone: a fan, a curtain, a pet, a mirror, or activity through plasterboard into the next room. Check the app state first. If it never goes clear, shorten range or move the aim before you lengthen the lamp delay. A vacancy delay that is already long only hides a sensor that never cleared.
Why does it clear while I am still on the sofa?
That is false vacancy. Stillness can drop below what the sensor counts as presence, especially if sensitivity was cut to fight a fan. UK reviews on the MS605 and SNZB-06P24 include sitting that clears the room. Raise the hold or move closer into the stated range only after moving fans and curtains out of the beam.
Will a dog or a ceiling fan hold the light on?
Yes, both can. A fan is a classic false-presence source; calibration does not always remove it. Pets are not filtered on every model. The MS600’s pet shield is a seller claim with one supportive UK review, not a lab result. Aim above a pet’s height and shorten range if the light must ignore the animal.
Can it see through a wall or a door?
Radar can pierce glass, wood and plasterboard. SONOFF’s manual and UK reviews describe next-room and outdoor-plant detections. Shorten maximum distance or move the sensor off the party wall. Do not treat through-wall reach into a neighbour’s space as a feature to tune upward.
Should I shorten the timeout or lengthen it?
Match the fault. If the app stays occupied in an empty room, shorten range or clear the moving object first; a longer lamp timeout only wastes light. If you are still present and the light dies, lengthen the hold or ease sensitivity after you have removed fans and curtains. On the SNZB-06P, respect the firmware minimum duration so a too-short setting does not leave the unit stuck present.

Related pages

Presence sensor buying guide

Presence detector

Best presence sensor UK for the hub you already have

How to set up a presence sensor on the hub you have

Presence sensor vs PIR: a chair, or a walk-through hall

Sources

Public UK sources from the digest first, then the amazon.co.uk listings compared on this page. Prices and stars were taken on 21 October 2026.

  1. ICO, Home CCTV systems (retrieved 21 October 2026)
  2. GOV.UK, Electrical Equipment (Safety) Regulations 2016 (retrieved 21 October 2026)
  3. SI 2016/1101, Electrical Equipment (Safety) Regulations (retrieved 21 October 2026)
  4. Ofcom IR 2030 (retrieved 21 October 2026)
  5. GOV.UK, When you do not need building regulations approval (retrieved 21 October 2026)
  6. IET, Part P frequently asked questions (retrieved 21 October 2026)
  7. Texas Instruments SSZT759, mmWave and PIR on their board (retrieved 21 October 2026)
  8. amazon.co.uk, smart presence sensor (retrieved 21 October 2026)