Garage Door Won't Open: Diagnostic Selector
Pick the symptom you see or hear and this selector points to the most likely cause — broken spring, snapped cable, off-track, dead opener or a bad sensor — and the right tool to budget the fix.
Calculator
Likely a broken torsion spring. A loud bang followed by a door that won't lift almost always means a broken spring. The opener may strain or not move the door at all. Use the linked calculator to budget the repair. ⚠️ This points to a spring, cable or off-track fault — those store extreme energy and can cause serious injury. Do not attempt it yourself; call a trained garage-door technician. This is a reference selector for planning, not a repair or safety guide.
When a garage door refuses to open or close, the symptom usually points straight to the cause. A loud bang followed by a dead door is almost always a broken torsion spring; a door that reverses before it closes is usually a blocked or misaligned safety sensor; a crooked door with a loose cable has jumped the track. This selector reads the symptom and tells you the most likely cause, what it means, and which calculator to use to budget the repair.
It is a reference selector for planning, not a repair or safety guide. Several of the causes — broken springs, snapped cables and off-track doors — involve components that store extreme mechanical energy and can cause serious injury. For those, the goal here is to help you understand the problem and budget the visit, then call a trained technician.
Formula
This tool is a classifier, not a numeric calculation. It maps each symptom to the cause that most often explains it and to the calculator that budgets the fix:
- Loud bang, now dead → broken torsion spring → spring replacement cost.
- Motor runs, door still → broken spring or a released trolley → spring replacement cost.
- One side low / binding → snapped cable or bent track → off-track repair cost.
- Reverses / re-opens → blocked photo-eye or a travel/force limit → general repair cost.
- Nothing at all → power, remote battery or logic board → opener replacement cost.
- Crooked, loose cable → snapped cable, off-track → off-track repair cost.
The spring, cable and off-track branches carry the prominent safety warning shown above.
Worked example
Choose “Heard a loud bang, now it won’t open” and the selector reports a broken torsion spring as the most likely cause, explains that the opener cannot lift the door’s full weight without a working spring, and links to the spring replacement cost calculator — alongside the warning that spring work is for a trained technician only.
Reading the symptoms
A few quick, safe checks before you call: confirm the opener has power (breaker, GFCI outlet, the plug); wipe the two photo-eye sensors near the floor and check they face each other with a steady light; and try the wall button as well as the remote to rule out a dead remote battery. Do not pull the emergency release on a door you suspect has a broken spring — the door can drop. Do not force a crooked or off-track door.
Basis: the symptom-to-cause mapping reflects the most common failure patterns for residential sectional and overhead doors; it is a planning aid, not a diagnosis of your specific door. The linked calculators give planning cost estimates from figures you enter. See sources. When springs, cables or an off-track door are involved, stop and call a trained garage-door technician with the correct winding bars.
Reference table
How the selector maps a symptom to the most likely cause. The spring, cable and off-track branches carry the safety warning above — that work is for a trained technician only.
| What you see / hear | Most likely cause | Budget it with |
|---|---|---|
| Loud bang, now it will not open | Broken torsion spring | Spring replacement |
| Motor runs but the door does not move | Broken spring or released trolley | Spring replacement |
| One side hangs low / binds / off-track | Snapped cable or bent track | Off-track repair |
| Opens then reverses / closes then opens | Blocked sensor or travel limit | General repair |
| Nothing happens — opener is dead | Power, remote or logic board | Opener replacement |
| Crooked door, a cable hangs loose | Snapped cable — off-track | Off-track repair |
Frequently asked questions
Why won't my garage door open?
The most common reasons are a broken torsion spring (a loud bang, then the opener strains), a snapped cable or off-track door, a blocked or misaligned safety sensor that forces a reverse, or lost power to the opener. Pick your symptom above to see the likely cause and budget the fix.
Why does my garage door open a little then reverse?
Usually a safety sensor issue — a blocked, dirty or misaligned photo-eye near the floor — or a travel/force limit on the opener that needs adjusting. These are non-spring repairs; the selector points to the general repair itemizer.
I heard a loud bang and now the door is stuck. What broke?
Almost certainly a broken torsion spring. Without it the opener cannot lift the door’s full weight. Do not force the door or pull the release. Budget the fix with the spring replacement calculator and call a technician.
Is it safe to fix a garage door that won't open myself?
Only the benign causes — cleaning a sensor, replacing a remote battery, resetting a breaker. Anything involving springs, cables or an off-track door stores extreme energy and is for a trained technician. This tool estimates and points; it is not a repair guide.
The motor runs but the door does not move — why?
Either the emergency-release trolley is disconnected (reconnect it with the door fully closed), or a spring is broken so the opener cannot lift the weight. If reconnecting the trolley does not help, treat it as a spring problem and call a technician.