Why Does My ADT Motion Sensor Keep Setting Off False Alarms?

Problem Description

Your ADT motion sensor is triggering false alarms when no one is in the room or failing to detect actual motion when someone walks through the detection zone. False alarms can result in unnecessary police dispatch fees and cause you to distrust your security system. This is typically caused by sensor placement issues environmental factors or sensitivity settings.

Symptoms

• Alarm triggers when house is empty and armed
• Motion sensor activates from pets moving in room
• Sensor does not detect motion during walk test
• False alarm triggered during heating or cooling cycle
• Motion alerts at same time each day from sunlight
• Sensor shows motion detected but no alarm triggered

Recognize these? Here's what usually causes it.

Common Causes

• Sensor aimed at heat source like vent or fireplace
• Direct sunlight hitting sensor lens at certain times
• Pets heavier than sensor pet immunity threshold
• Sensor mounted too low or at wrong angle
• Insects or spiders crawling on sensor lens
• HVAC airflow creating rapid temperature changes in zone

Tools & Requirements

Step-by-Step Solution

1

Identify the False Alarm Pattern

Review your ADT alarm history in the app or on the panel to identify when false alarms occur and which sensor triggers them. Look for patterns like same time of day which suggests sunlight or recurring during heating cycles which suggests HVAC interference. If alarms happen only when pets are home the pet immunity feature may need adjustment. Understanding the pattern points directly to the cause.

2

Check Sensor Placement and Mounting

ADT motion sensors should be mounted 7 to 8 feet high in the corner of a room angled slightly downward. They should not face windows where direct sunlight enters or point toward heating vents fireplaces or radiators. PIR motion sensors detect changes in infrared heat so any heat source that fluctuates can trigger a false alarm. Reposition the sensor if it faces any of these problem areas.

3

Enable or Adjust Pet Immunity

Most ADT motion sensors have a pet immunity feature that ignores motion from animals under a certain weight typically 40 to 80 pounds. Contact ADT support or access your panel settings to verify pet immunity is enabled and set to the correct weight threshold for your pets. Keep in mind that pet immunity works best when sensors are mounted at the correct height as low-mounted sensors cannot distinguish pet from human motion.

4

Clean Sensor Lens and Check for Obstructions

Use a soft dry microfiber cloth to gently clean the sensor lens. Dust cobwebs and spider webs on or near the sensor can cause false triggers as insects move across the detection field. Also remove any decorations furniture or objects that were recently placed near the sensor that might sway or move in airflow. Even a hanging plant moving in HVAC airflow can trigger a PIR motion sensor.

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5

Perform a Walk Test

Put your ADT system in test mode through the panel or by calling ADT monitoring. Walk through each room with a motion sensor at normal speed and verify the sensor detects you. Then walk through areas where false alarms occur and observe if anything else triggers the sensor. This helps confirm whether the issue is over-sensitivity causing false alarms or under-sensitivity causing missed detections. Exit test mode when finished.

Quick Solutions

Still having issues? This is usually the deeper cause below.

Need More Help? ADT Support

Note: The contact information below connects you directly to ADT's official customer support team, not Trunetto. They can help with warranty claims, device replacements, and advanced technical issues.