Sonoff SenseGuard DW Gen2 Zigbee Door and Window Sensor (SNZB-04PR2)

Product detailed description

Sonoff SenseGuard DW Gen2 – Zigbee Contact Sensor with Tamper Detection 🔐

Sonoff SenseGuard DW Gen2 (SNZB-04PR2) is the second generation of the popular Zigbee door and window sensor. In addition to standard "open / closed" reporting, it adds what conventional magnetic sensors lack – tamper detection. If someone tries to remove the sensor from the frame or damage it, you receive an immediate notification on your phone and can trigger automations, such as an audible gateway alarm or camera recording.

The transmitter is just 13.5 mm thick and weighs 45 g, making it almost invisible on the window frame and ensuring it won't interfere with closing. Running on Zigbee 3.0 with a range of up to 100 m in open space, it is powered by a pair of standard AAA batteries lasting up to 3 years. Instead of a traditional reed switch, it uses a contactless Hall sensor that suffers no mechanical wear.

Smaller Size, Greater Performance

Its predecessor, the SNZB-04P, was nearly 22 mm thick and used a CR2477 coin cell battery. The new SNZB-04PR2 door sensor is significantly slimmer at 13.5 mm, while handling a gap of up to 30 mm between the transmitter and magnet. In practice, this is the difference between "the sensor doesn't work on this window" and smooth installation even on older wooden windows where the frame and sash aren't perfectly flush.

The communication range of 100 m in open space is 30 m longer than the previous generation, allowing the opening sensor to easily reach gates, garages, basements, or garden sheds. When you have at least one mains-powered plug or relay in your Zigbee network, the signal is strengthened even further across the mesh network.

Installation That Adapts to Any Window

The magnet can be attached horizontally or vertically and is detachable, so you can place it exactly where space allows – even on non-standard frames where the sash and frame differ in height. Horizontal mounting allows a detection distance of up to 30 mm, while vertical mounting allows 15 mm. Mounting is handled by the included 3M double-sided tape, making window sensor installation a one-minute job with no drilling or frame modifications needed – ideal for rental properties.

Triggers Full Home Defense, Not Just Notifications

A contact sensor delivers the most value when part of an ecosystem. Opening a door when the system is set to "Away mode" can instantly arm the gateway, sound a siren, and trigger camera recording – for example, SONOFF CAM PT-2 starts recording the moment something happens, rather than waiting for you to check the alert.

Tamper Detection – The Key Gen2 Feature

A standard magnetic door sensor can be bypassed by simply peeling it off the frame, causing the system to keep reporting "closed" even if the window is wide open. The SNZB-04PR2 features tamper detection: the moment the sensor body detaches from the surface or is damaged, it sends a dedicated report to the eWeLink app. You can also check tamper status at any time in the app alongside open/closed status and battery level.

This feature is equally useful beyond security – if you stick the sensor onto a safety gate, medicine cabinet, or tool drawer, you'll instantly know if someone tries to tamper with it.

Helps Lower Your Energy Bills

Sensors aren't just for intruder protection. Window status serves as an excellent trigger for energy-saving automations: if a window stays open for more than five minutes, your Zigbee thermostatic radiator valve automatically turns off heating, or when you close the wardrobe door, the light turns off. Nothing to remember – the door sensor handles it for you.

Who Is This Sensor For?

• For homes seeking security without wiring changes – everything sticks via 3M tape, no drilling needed, perfect for rentals.
• For Home Assistant users looking for full Zigbee2MQTT support, including tamper alerts.
• For owners of older doors and windows with wider gaps or uneven frames where standard 15–20 mm sensors fail.
• For families with small children or pets – monitoring medicine cabinets, cleaning supplies, or pet crates.
• For those looking to optimize heating costs – automatically switching off heating when windows are open.

Use Cases 💡

• Receive a alert when the front door opens while you are away – including exact timestamps in history logs.
• Check if all windows are closed before leaving home with a single glance at the app.
• Automatically turn off heating when windows open – the sensor signals the radiator valve after five minutes.
• Turn on lights automatically upon opening doors to the garage, pantry, or wardrobe.
• Trigger sirens and camera recordings upon unauthorized door opening when in armed mode.
• Get notified if the fridge or freezer door is left ajar.
• Monitor safes, medicine cabinets, or toolboxes – with alerts if someone tries to remove the sensor.
• Monitor pet crates or child safety gates.
• Chime notification when shop doors open – trigger door chimes on gateways or NSPanel Pro.

Voice Control: Alexa & Google Home

Once paired with eWeLink, sensor status can be checked via voice commands – "Alexa, is the front door closed?" – without getting up or opening the app. The door sensor serves as a convenient check before bedtime or leaving the house.

Apple Home via Matter Bridge

You can bring this sensor into Apple Home via a Matter Bridge in two ways: either using a Matter-certified hardware gateway (Zigbee Bridge Ultra, ZBBridge-U, iHost, or NSPanel Pro running eWeLink CUBE), or free eWeLink CUBE software on a Raspberry Pi, VM, or NAS alongside a Sonoff Zigbee dongle. In Apple Home, it appears as a native contact sensor for use in automations across iPhone, iPad, or Apple Watch.

Home Assistant: Zigbee2MQTT & ZHA

In Zigbee2MQTT, support is complete out of the box – exposing contact state, tamper status, low-battery warnings, battery percentage, and voltage with zero extra setup. State changes update almost instantly in Home Assistant before the door finishes closing. In ZHA, open status and battery work right out of the box; tamper reporting requires an additional quirk for the vendor-specific cluster.

Compatible Hubs and Ecosystems

The SNZB-04PR2 is a Zigbee 3.0 device requiring a hub or Zigbee coordinator. Verified to work with ZBBridge-P, ZBBridge-U, NSPanel Pro, and iHost gateways, ZBDongle-P/-E series USB adapters, Dongle Max, Dongle Plus MG24, Dongle Lite MG21, Amazon Echo Plus 2nd Gen, Echo 4th Gen, Echo Show 2nd Gen, Aeotec Smart Home Hub V3 for SmartThings, and FRITZ!Box 7690. Full feature access including tamper reporting and OTA updates is supported via eWeLink and ZHA/Zigbee2MQTT.

Why Choose SenseGuard DW Gen2

• Tamper detection missing from cheap magnetic sensors – preventing unnoticed sensor removal.
• Thinnest in its class (13.5 mm) with the largest detection gap of 30 mm – works where other sensors fail.
• Standard AAA batteries instead of expensive coin cells, providing up to 3 years of maintenance-free operation.
• Detachable magnet and vertical mounting – adapts easily to non-standard frames.
• Full Zigbee2MQTT integration including tamper state, battery percentage, and voltage readout.

Compared to the older SNZB-04P model, you get a slimmer profile (13.5 mm vs. 21.9 mm), longer range (100 m vs. 70 m), larger detection gap (30 mm vs. 20 mm), detachable magnet, vertical mounting option, and standard AAA batteries instead of CR2477. The older generation offered a 2-year longer battery life rating – if you prefer a sensor you don't need to open for years and have small frame gaps, the SNZB-04P remains a viable choice.

Main Specifications

What's in the Box

Inside the package, you will find the transmitter and magnet, double-sided adhesive mounting tapes, a multilingual quick start guide, and two pre-installed AAA batteries. No additional purchases required – except for a Zigbee gateway if you don't already have one.

Frequently Asked Questions

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