Before suspecting the motor or the springs, check the safety sensors near the bottom of the door tracks. Since the 1990s, garage door openers have been required to include photo-eye safety sensors that stop the door and reverse it if anything blocks the beam between them — and a door that starts closing then reverses, or refuses to close at all, is very often this system working exactly as intended.
Check the safety sensors first
Look for two small sensor units mounted near the floor on either side of the door track, usually with small indicator lights. When aligned and working correctly, both lights are typically solid — a blinking or unlit light on either sensor usually means the beam between them is blocked, misaligned, or one of the units has lost power.
Common causes
| Cause | How likely | Typical sign |
|---|---|---|
| Object blocking the sensor beam | Very common | Something stored or parked in the beam’s path |
| Sensors misaligned | Very common | Knocked out of position, often by something brushing against them |
| Dirty sensor lenses | Common | Dust, cobwebs, or grime coating the lens |
| Sun glare hitting a sensor directly | Common | Fails at a specific time of day, works fine otherwise |
| Sensor wiring damaged or disconnected | Occasional | One sensor light completely dark |
| Remote or wall control fault | Occasional | No response at all, sensors not the issue |
| Track obstruction or bent track | Occasional | Door struggles or makes unusual noise while moving |
| Broken spring | Uncommon but serious | Door feels very heavy if moved manually, may not open at all |
How to work through it
- Clear the sensor area completely
Remove anything stored near the bottom of the tracks that could be blocking or close to the beam, including items that may have been placed there recently without realising they would interfere.
- Check both sensor lights
Most systems show a steady light on each unit when properly aligned. Consult your model’s indicator pattern if you are not sure what normal looks like — patterns vary between manufacturers.
- Clean both sensor lenses
Wipe each lens gently with a soft, dry cloth. Dust and cobwebs accumulate here more than people expect, particularly in garages.
- Check alignment
Gently loosen the mounting bracket on one sensor if needed and adjust it so both units face each other directly. Small nudges from a car door, a bike, or stored items commonly knock these out of alignment over time.
- Check for direct sunlight interference
If the fault happens consistently at a certain time of day, strong sunlight hitting a sensor directly can interfere with it. Shading the sensor slightly, or checking the manufacturer’s guidance for this specific issue, often resolves it.
- Test the door
Once sensors are clean, clear, and aligned, try closing the door again and watch both indicator lights as it does.
If you need to close it manually right now
It can be tempting to disable the sensors to force a door closed, particularly if you need to secure the garage urgently. Do not do this — the sensors exist specifically to prevent the door closing on a person, pet, or vehicle, and bypassing them removes that protection entirely, not just temporarily. Most openers have a manual release cord for exactly this situation, allowing you to close the door by hand while the sensor fault is sorted out properly.
When to call a garage door technician
Call a technician if sensor wiring appears damaged, if the door will not close even with sensors confirmed clean, aligned, and unobstructed, if you suspect a broken spring (the door feels unusually heavy when moved by hand, or will barely lift), or for any track damage or bending. Springs in particular hold significant tension and are not a homeowner repair — this is one of the few home repair jobs on this site with a genuine injury risk built into the mechanism itself.
Stop and call a qualified appliance technician or electrician if you find scorched or melted wiring, smell burning, see water that has reached electrical components, or if the fault returns immediately after a repair. Never bypass a safety device — thermal fuses, door interlocks and flood switches fail for a reason, and defeating one converts a broken appliance into a fire or flood risk.
