In a February 2026 analysis of 50,000 smart-home troubleshooting queries, 36% landed in three categories (device offline, camera issues, hub instability) where the first-line fix is the same: power-cycle the device. Sensor Watchdog does that for you, automatically.
Import
For everything else, see the README on GitHub.
The WiFi Router
The router locks up. Internet goes dark. Family asks why Netflix is down. You walk over and pull the plug.
With Sensor Watchdog, you put a Zigbee or Z-Wave smart plug between the wall and the router, plus a ping sensor pointing at your gateway. When the gateway stops responding, the watchdog cycles the plug. The router reboots. The internet comes back. You did not have to be home.
If the cycle does not bring the router back (dead hardware), the watchdog notifies you. A dead router does not silently leave the internet down.
The mmWave Sensor
The Aqara FP2 hangs every couple of weeks. The lux entity reads a wildly wrong value. The presence sensor reports the same state forever. But Home Assistant says the device is online and the integration is happy. No state changes, no recovery.
This is the case the watchdog's freshness detector catches. If it expires, the device is declared frozen and the plug cycles. The sensor reboots and starts reporting again.
Watch the presence and illuminance entities together. Either one acts as a heartbeat.
What You Can Configure
- Detect offline. Catches devices that go
unavailableorunknown. A tolerance window rides out brief network blips. - Detect frozen. Catches devices that look online but stop reporting fresh values. The failure mode simple watchdogs miss.
- Active time window. Only judge "frozen" during waking hours, so a quiet bedroom at 3 AM does not trigger a false cycle.
- HA-start block. Skip recovery during the first minutes after Home Assistant boots, when devices are still loading and look offline.
- Failure notification. Wait a settle period after each cycle, then run any HA action (notify, persistent_notification, script) if the device did not come back.
- Self-recovery. If the smart plug gets turned off by accident, the watchdog turns it back on.
Other blueprints in The Thinking Home series:
- Recently Active — Create a "was active recently" sensor from any source, with a configurable look-back window.
- Sensor Failover — Fall back to a secondary sensor when the primary goes unavailable.
- Linked Entities Pro — Two-way sync for any number of entities across switches, lights, input_booleans, fans, and groups.
- Sensor Watchdog — Detect sensors that have stopped responding and power-cycle them back.
Version
1.0.0 stable. Verified across 46 simulator scenarios and four home instances. Released June 2026.