Review: Mighty Mule FM231 Wireless Driveway Alarm System

mightymule fm231Summary: The Mighty Mule FM231 is the most affordable driveway alarm that detects cars only, but the electromagnetic sensor is inconsistent. The Dakota 2500 is a lot more reliable and accurate.


  • Weather Proof
  • Easy installation
  • Low battery indicator


  • Unreliable sensor
  • Some units stop working after 1 week
  • The volume of the receiver is very low


  • Detects vehicles
  • Radio range: 400 mile feet
  • Motion detection Area: 12 feet
  • Weather proof
  • Low battery indicator
  • Notification: sound and flashing LEDs
  • Sound choices: 1 chime
  • Adjustable sensitivity control
  • 1 year warranty

Is This Alarm System Right For You?

The Mighty Mule FM231 features an outdoor electromagnetic sensor that will notify you whenever it detects moving vehicles.


The kit includes 1 transmitter, 1 sensor, 1 receiver, 1 transformer, mounting hardware and instructions manual. Batteries are sold separately.

How It Works

The electromagnetic sensor will detect moving vehicles and will send a signal to the indoor receiver. The indoor receiver will notify you by a chime.

Installation Tips

  • In order to avoid false alarms, install the sensor next to your driveway, at least 25 feet away from roadways or your neighbour’s driveway
  • Do not place the transmitter near a water sprinkler. The transmitter is water resistant but not waterproof.
  • Mount the sensor far away from power transformers, power lines, gas lines and telephone lines.
  • In order to prevent any damage, run the Signal Cable inside a PVC pipe

Bottom Line

The Mighty Mule FM231 has a decent range and does not detect animals or people. But the outdoor electromagnetic sensor does not always detect cars and it sometimes goes off randomly. In many cases, the unit will stop working after only 1 week. This is mainly due to the fact that it’s made with low quality components. The Dakota 2500 is more expensive but it’s a lot more accurate and you won’t experience any false alarms.

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