Issues with Sonoff SNZB-03

So I am using a raspi4 with a ConBee II on stick with Phoscon and got a few SNZB-03 motion sensors. So far they are not very good with a 150s refactory rate and have terrible reliability. I’ve been testing them with two input numbers and a script to increment them every time they detect a motion and ran the script over night. One sensor I think is faulty with 153 false positives, over the course of 8hrs night and the other had 28 false positives in the same time interval. Is there something I can do about this, or should I just get new motion sensors.

Mine are working fine. They seem to burn through battery a bit faster than aqara sensors. Im using the sonoff bridge with tasmota and ZHA fyi.

I figured out that one sensors was just faulty out of the box, and the other works decently well. Because one was bad I decided to try test one more. Not a fan of the 150s refractory rate, but in low traffic areas they are doing fine. I am still working on the faulty sensor, and seeing if it is something I can fix. You win some and you loose some with cheaper sensors I suppose.

I just paired the 2 SNZB-03 motion sensors I bought.
One is working ok.
The other one started malfunctioning within an hour of powerup!
An hour after initial powerup, I put it outside near my front door and after about 30 minutes, it started having phantom triggers about every 60 seconds.
It’s 26 degrees F outside, so I brought it back inside to see if it would behave when it warmed up.
I’m watching it as it warms, and it’s still triggering once per minute.
I also put the working unit outside to see if it malfunctions when it gets cold.

1 Like

It started working normally after I brought it inside and it warmed up.

The first sensor is now outside and it has not started self-triggering every 60 seconds, yet.

1 Like

I’ve had a similar experience with them. The best I can say about them is that they are good for a cheap sensor, just buy a few and set your expectations low. Easy to integrate even if they are faulty, I found that if you connect them and put them back in their box for 24 hours it is very easy to weed out the faulty ones. Almost seems as if QC doesn’t do that ¯_(ツ)_/¯

Any idea if the Aqara motion sensors are better?
I’m not married to Sonoff. :slight_smile:
They are just the brand I bought first.

I have a single Sonoff SNZB-03 that I brought in for testing. After some teething problems, I am mostly happy now and have another ten coming. The one issue I have not been able to sort out is that the sensor will be reported as “Unavailable” if HA has not heard from it in more than 6 hours (using ZHA and the Sonoff bridge).
The issues I have encountered were mostly related to stuff being too close to the sensor. In one instance I had mounted the PIR at about head height in a closet. My wife would go into the closet, the PIR would (reliably) trigger but would time out after about two minutes even though my wife was still in the closet. The only way to re-trigger the PIR was for her to leave the closet and then come back. What I determined was that the sensor was overloaded because my wife was within a foot or so of the sensor. The sensor re-calibrates on a regular basis to see what the background IR profile looks like and it would see her head, recalibrate to that (being so close, the head covered a large part of the sensor) and would recognize that heat signature to be the background noise level. The only thing to do was let the sensor calibrate with my wife not being in the closet.
Anyhow, the fix was to move the sensor another 3 ft away and it became rock solid.
I have also seen false triggering if there is an obstruction within a couple or so feet of the sensor.

I have seen a note of a capacitor being installed on the sensor to reduce the noise sensitivity but I have no URL for that fix.

1 Like

I found this info on a github issue report thread. It will shed some light onto the expected behavior of the Sonoff SNZB-03. Itead is the designer of the Sonff products:

Itead told one of the posters that the unit has a 1 minute timeout, before it re-arms.

Hi, so I got a reply from ITEAD basically confirming what we experienced:
" Due to power consumption and power-saving considerations, there have some restrictions on the trigger
That is: when SNZB-03 detects the movement, it will send a signal to ZBBridge
If the device does not detect any movement for one minute, once the device triggered, it will send a signal to ZBBridge
If any movement is detected within one minute, the device will not send a trigger to ZBBridge. And effective detection and trigger signals to ZBBridge will be delayed for one minute. It means the motion sensor works with one-minute intervals.

This confirms that:
If movement has started and does not stop, then the device will NOT send any trigger (not occupancy=true nor occupancy=false) until movement has stopped.

The other problem of occupancy=false being sent after 60sec although there is still movement must be another (probably independent) issue. I encountered it too, but only occasionally.



I have two of the Aqara Sensors have about the same refractory rate, I’ve never had one fail like the sonoff sensors, plus they also have a lux sensor. For the Aqara, you are definately getting a much more reliable and well just more our of the sensor. They are a much better investment.
However if you really want to go all out, I also have a Philips hue motion sensor that I really like, you pay a much higher dollar, but you get a motion sensor with a really low refectory rate (10 seconds I think), lux, and temperature. I like to average it out at around $10 a sensor, anything lower than that will probably give you issues, with the exception of building your own.

While they can be good, I think they definitely have a use case. I would recommend The Aqara Motion Sensors over sonoff because they also have a lux sensor. Not only that, there wasn’t any fuss or testing. The process was, connect to zigbee, place and walk away.

The sonoffs were definitely a good entry point and lesson for me that, if I am going to invest time in something that is supposed to be ‘plug and play’ it is going to be DIY. When I buy a commercial product, I don’t want to spend time trying to figure out why it’s not working. I want each and everyone of them to work as advertised, not 3 feet away, and not a 1/3 failure rate.

Please do let me know how it goes, I would love to know if the faulty one was just a 1 in a million thing.

Thankyou! Good find

My Motionsensor1 finally acted up.
About 8pm last night, the outdoor temperature dropped below 10 degrees F, and then my Motionsensor1 started self-triggering once-per-minute.
Around 6:15am this morning, the outdoor temperature rose above 10 degrees F, and it finally stopped self-triggering once-per-minute.

These Sonoff SNZB-03 are unusable as outdoor sensors in areas that get winter temperatures below 10-20 degrees F!

Any idea if the Aqara motion sensors work at temperatures around 0 degrees F?

1 Like

I just compared the specs from the manuals of the Aqara and Sonoff motion sensors
They both have the same -10C (14F) lower operating temperature.

Can I expect the Aqara motion sensor will also flake out when it gets cold (near -10C / 14F)?

Sonoff motion sensor specs:
specs from manual

Aqara motion sensor specs:
Specs from manual

1 Like

I would think so. It’s probably something to do with the battery and it’s thermal mass. You may have to invest in an motion sensor that is better suited to the cold.

I’m trying a battery longevity experiment with one of my Sonoff SNZB-02 temp sensors.
I suspect that the SNZB-03 would benefit from a similar battery upgrade.

Just wanted to chime in in case someone is checking out this thread to see reliability of these sensors.

STAY CLEAR of these sensors, absolute rubbish from Sonoff. Most of their stuff is ok, but I have had so many issues with these sensors, I have 4 and they are now all in the bin, sadly. Complete waste of money. All with the same issue of intermittently giving false positives. Have tried them on both Smarthings and Tubz though ZHA with the same results. My recommendation would be the Ikea, have 5 of these and they are always rock solid, going on three years now (one Aquara died after a two years, not too bad)

The door sensors are also pretty rubbish, stay away from them as well, Aquara would be my recommendation, have had one for a bout two years, rock solid. The Sonoff ones drop off the network every few months.

If you find it useful, I solved it by updating the Combee2 manually with my Windows notebook with the official deconz procedure, then I removed the sensor and re-paired. Now it works fine. It only remains to find a way to reduce the trigger time by 60 sec with some mods.
I hope it is understandable. I used Google Translate

I got this motion sensor to test how it performs. Paired it with a Sonoff Zigbee Dongle E. The first time it detected motion, it would not reset when the motion ceased. Put it in a box and the next day, the state of the sensor still shows occupied. Turned it off the next day by removing the battery, but Home Assistant still shows the same state with battery at 100%. Removed the device from Zigbee2MQTT and re-paired it. It only worked for a couple of detections, then it went back to occupied state once motion was detected and then got stuck in that state.

As per the manual the device only resets to the clear state after no motion has been detected for 1 minute. So I covered the device with a box and removed it after one minute. A red light from the sensor blinked once. I tried this many times and the red light always blinked once as long the box is removed after 1 minute. So in my opinion the hardware part of the sensor does correctly detect motion, but somehow the software part is buggy. Maybe a firmware update in future might fix the issue. I will also try using the device directly in the ewelink app and see how it performs, but I’ll need to buy another zigbee hub before I can try that.

Change the battery. Mine started to act like this when the battery was almost empty. Constantly showing occupied. After changing the battery it worked normal again.