The Zigbee Sonoff aperture sensor SNZB-04P offers reliable detection for doors, windows and shutters. This detailed test covers unpacking, physical and software installation with Zigbee2MQTT and Home Assistant, possible automation and long-term monitoring. Find out why this economic model under 15 € excels in home automation Zigbee 3.0.

🔍 My unpacking of the Sonoff SNZB-04P

The sensor comes in an orange packaging characteristic of the Zigbee Sonoff range. The model SNZB-04P is well marked on the box. At the opening, I discovered compact equipment with precise dimensions: 50.5 x 32 x 21.9 mm sensor and 27 x 12 x 12.4 mm magnet, weighing only 33 g in total.

Here are the strengths noted from the first start:

• A large pairing button on top, practical without fine tool like a trombone.
• An anti-snap button to detect any sabotage attempt.
• A built-in CR2477 3V 1000 mAh battery, with a safety tab to be removed to activate it. This lithium battery offers up to 5 years of battery life depending on the manufacturer, depending on the frequency of use.
• Pre-glued 3M double-sided adhesives for immediate and resistant fastening.
• Careful white PC manufacturing quality, suitable for indoor use from -10°C to 60°C.

Here are the details in close-up images:

Where to buy this equipment?

Here is the link to the page dedicated to SNZB-04P. I referenced the sellers and prices.

🏡 My installation on a shutter

I install the sensor on an existing flap with support. I place the magnet underneath rather than opposite to respect the mechanics. The sensor uses a Hall effect to detect the magnetic field: recommended maximum distance of 20 mm (improved vs previous models), but I aim less than 1 cm for optimal reliability.

Tips for Installing Properly

For detection without false positives, follow these precise steps:

• Attach the sensor to the fixed part (frame or frame).
• Glue the magnet onto the movable part (battant or leaf).
• Keep less than 20 mm apart, ideally 1 cm maximum.
• Degrease surfaces with alcohol before gluing.
• Test 20 openings/closures to validate.

Tip: Avoid ferrous metals near the sensor, they interfere with the Zigbee signal (indoor range 30 m).

🔗 I integrate into Zigbee2MQTT

I enable pairing mode in Zigbee2MQTT (180 seconds). I remove the tab: Red LED flashes. Otherwise, I press the big button for a long time. The Zigbee 3.0 protocol (MCU EFR32MG22) ensures compatibility with Sonoff or third-party hubs.

Immediate recognition. Entities detected:

• Opening/closing without latency (binary contact state).
• Detector tearing off (tamper: "Normal" or "Altered").
• Battery visible after 24h (actual voltage to monitor, not always accurate).

I am renaming the ‘Country shutter’ device for rapid identification in the case of multi-sensors.

🏠 I add to Home Assistant

Automatic appearance via Zigbee2MQTT. Available entities:

• Open/closed state (on/off in backend).
• Battery level (initially overrated, check voltage).
• Handling/tampering (disable if double-sided too thick).

In my setup, the tamper generates false positives with the adhesive thickness. I disable it via the HA interface.

⚙ My automatisms with the sensor

In Home Assistant, I configure without code via the automation editor:

• Alert if open >10 min: persistent push notification.
• Siren if opening in alarm mode armed.
• Counter openings: entity history_stats for daily/hebdo stats.

These rules run locally, without cloud.

💡 Tips and Problem Solving

• Fixed battery 100% : Normal 24-48h, then stabilizes. Replace CR2477 if <2,7V.
• Failed pairing: Pile out 30s, reinsert, get closer to the coordinator.
• Erratic detection: Check <20mm magnet gap, relocate out of metal.
• Low reach: Add Zigbee routers (Sonoff sockets) between sensor and dongle.

💬 My verdict on SNZB-04P

This Sonoff Sensor SNZB-04P exceeds expectations at this price: Precise detection, useful tamper, Zigbee2MQTT/HA fluid integration. The CR2477 battery promises 5 years. All that remains is to allow it to run for a while to check for false positives or missed detections.

📑 My detailed manual

Check out this user manual enriched for more technical details.

📅 Tracking stack in production

Installation of kitchen shutter on 31/08/2025 with original battery CR2477. No replacement required to date. I monitor voltage via HA to anticipate.