The 20€ Sensor That Ended Our "Did We Leave the Garage Open?" Anxiety (Beginner Tip)

My beginner tip: the most valuable automations are not the fancy ones — they are the ones that answer a question you ask yourself every evening. Ours was: “Is the garage door still open?”

The setup: One Aqara Door & Window Sensor P2 on the garage door in the basement. That’s it. No camera, no smart garage opener — a contact sensor for around 20€.

The automation (Home Assistant): At 8 pm, HA checks the sensor. If the garage is still open, Alexa announces it on every Echo in the house and I get a push notification with a timestamp. If it’s still open at 9 pm, the whole thing repeats. Two fixed checkpoints instead of instant alerts — because during the day the garage is supposed to be open half the time.

That follow-up reminder is the detail I’d recommend to every beginner: one notification is easy to swipe away and forget. The second one is what actually gets the door closed. And the voice announcement is the real MVP — you can ignore your phone, but not a voice from three rooms away.

alias: Garage door - open in the evening warning
description: >-
  Warns at 8 pm and 9 pm via all Echos + push notification
  if the garage door is still open.
triggers:
  - trigger: time
    at: "20:00:00"
  - trigger: time
    at: "21:00:00"
conditions:
  - condition: state
    entity_id: binary_sensor.garage_door
    state: "on"
actions:
  - action: notify.alexa_media_everywhere
    data:
      message: Attention, the garage door is still open. Please close it.
      data:
        type: announce
  - action: notify.mobile_app_my_iphone
    data:
      title: 🚗 Garage door open!
      message: The garage door is still open at {{ now().strftime('%H:%M') }}.
      data:
        push:
          sound:
            name: default
            critical: 0
        priority: high
mode: single

Same logic works in the Aqara app with a time-conditioned automation if you don’t run Home Assistant.

Since installing it: zero mornings with an open garage. Sometimes smart home is not about doing things automatically — it’s about never having to wonder.

What “did I forget…?” question did a sensor solve for you? StarterTips

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