Home / Safety Sensor Alignment and Fault Codes
Safety Sensor Alignment and Fault Codes
Photoelectric safety sensors are required on residential garage door openers and are the most common single cause of a door that opens but will not close.
How the pair works
One unit emits an infrared beam, the other receives it. An unbroken beam permits closing. A broken beam halts and reverses the door. The system fails safe, meaning any fault in the circuit prevents closing rather than permitting it. This is why a damaged wire produces the same symptom as an obstruction.
Reading the indicators
Both sensors carry indicator lights, usually one colour for power and another for alignment. A steady light on both units indicates a good beam. A blinking or extinguished receiver light indicates misalignment, obstruction, contamination or a wiring fault. Many opener units also flash a count at the motor head that maps to a documented fault code.
Common causes of misalignment
- Physical contact, most often bicycles, bins or stored items knocking a bracket
- Vibration loosening the mounting screw over time
- Lens contamination from dust, cobwebs or spray
- Direct low angle sunlight saturating the receiver at certain times of day
- Wiring damage at the staple points along the wall
Correcting alignment
The bracket is loosened slightly and the sensor moved by small increments until the receiver indicator is steady, then fixed. Both sensors must sit at the same height, no more than six inches above the floor. Height matters because the sensor is intended to detect a small child or pet in the door path.
When it is the wiring
If alignment does not restore a steady indicator, the circuit is suspected. Sensor wire is low voltage and frequently run along the wall where it is exposed to damage. A break under a staple is the classic fault, and it produces intermittent behaviour that appears to be a mystery until the run is inspected.
What not to do
Sensors should never be bypassed, taped together at the motor head, or mounted facing each other at bench height to defeat the interlock. The interlock exists because doors have killed children. A door that will not close because of a sensor fault is behaving correctly.