This is almost always due to a problem with the safety sensor system (photo eyes). Holding the button manually bypasses this mandatory safety mechanism.
Interactive Diagnostic: Find the Cause in 1 Minute
1. Check Sensor Lights
What to Look For:
Each sensor should have a solid LED indicator light. Usually, one is green, the other yellow/amber. If one light is **off or flashing**, it indicates a problem.
2. Check for Obstruction
What to Look For:
Even small items like cobwebs, leaves, boxes, or tools can break the invisible beam between the sensors. Ensure the path is completely clear.
3. Check Sensor Alignment
What to Look For:
The sensors must point precisely at each other. If one has been accidentally bumped or shifted, the beam will be interrupted. They must be at the same height (usually 4-6 inches from the floor).
Detailed Solutions
How to Fix Safety Sensor Problems
This is the most likely cause of your problem. Follow these steps to resolve it.
Step 1: Clean Sensor Lenses
Wipe the lenses on both sensors with a soft, dry cloth to remove any dust, dirt, or cobwebs.
Step 2: Remove all Obstructions
Ensure there are absolutely no objects between the sensors. Check the beam path from one sensor to the other.
Step 3: Align the Sensors
If the indicator lights are not solid, gently adjust the position of one sensor by hand until the light becomes steady. You may need to tighten the mounting screw to secure it in place.
Step 4: Check the Wiring
Inspect the wires running from the sensors to the opener unit. Look for breaks, frayed spots, or loose connections. Ensure the wires are securely attached to the terminals on the opener.
When Should You Call a Professional?
While sensor issues are often DIY fixes, some situations require professional assistance.
- You completed all steps, but the problem persists. This may indicate a faulty sensor unit or a problem with the control board.
- Sensor lights won’t turn on even after checking wiring and alignment.
- You find damaged wiring and are not comfortable repairing electrical components.
- The door makes strange noises, moves unevenly, or has visible mechanical damage (e.g., broken springs). Do not attempt to repair springs yourself—they are extremely dangerous!
Safety Tips & Expert Recommendations
- Always disconnect power. Unplug the garage door opener unit before checking wiring or performing any repairs.
- Test regularly. Test the reversal system monthly. Place a block of wood or a roll of paper towels on the threshold. The door must automatically reverse when it makes contact.
- Do not bypass sensors. Disconnecting or bypassing the safety sensors is illegal and extremely dangerous. They exist to protect people, especially children and pets.
Frequently Asked Questions (FAQ)
How much does it cost to repair garage door sensors?
If you do it yourself, the cost can be zero (for cleaning and alignment) or the price of new sensors (typically $25-$50). Calling a professional for diagnosis and repair usually costs between $100 and $200, depending on the region and the complexity of the issue.
Can I just disable the sensors?
Absolutely not. This is extremely dangerous. Safety sensors have been a mandatory safety feature since 1993 to prevent serious accidents. Disabling them creates a major risk of injury or property damage.
Dmytro Shevchenko is the owner of Prime Garage Door Repair, a trusted garage door repair company serving the Chicagoland area. Based in Mundelein, IL, he leads a team of certified technicians specializing in emergency repairs, opener and spring replacement, and complete garage door installation.
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