4-4 — RPM sensor signal lost
The opener detected a loss of motor RPM while the door was moving — the motor stalled or slowed sharply under load and the opener stopped as a safety measure. This is usually a mechanical problem (door too heavy from a broken spring, binding rollers or track) rather than a failed sensor, though a loose RPM sensor connection can also trigger it.
- Keep using it?
- Limited use only
- DIY difficulty
- Moderate
- Typical cost
- $10-20
- Verified against
- liftmaster.com ↗
The fix
Garage door roller/track lubricant and tune-up kit (not a replacement part — a maintenance step)
Motor stalled or lost RPM under load while moving
Diagnose first: This is usually a heavy or unbalanced door — most often a weak/broken torsion spring, binding rollers, or a dirty track, not a failed opener part. Lubricating the rollers/track is a safe DIY step and worth trying first. Torsion springs are under extreme tension and are NOT a DIY repair — if the door feels heavy by hand with the opener disconnected, call a garage door technician rather than replacing opener parts.
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How to fix it
- With the door fully CLOSED, pull the manual release cord and lift the door by hand. It should lift smoothly with light effort and stay put at waist height. If it is very heavy or slams shut, a spring is broken or the door is out of balance — stop and call a garage door pro; do not run the opener and do not attempt spring repair yourself.
- Visually inspect the torsion spring above the door for a gap in the coils (broken spring) and check lift cables for fraying.
- If the door is balanced and moves freely by hand, unplug the opener for 1 minute and retest.
- Reseat the RPM sensor/travel module connector at the logic board and inspect the harness for damage.
- If 4-4 persists with a balanced door, replace the travel module/RPM sensor for your model.
- After any module replacement, run the learn-limits routine.
- If the code still returns, the logic board is the remaining suspect.
Why it happens
Typical signs: Door makes a quick bump and stops · Up arrow blinks 4, down arrow blinks 4 · Lights flash 10 times after attempted run · After board replacement or surge event
- Broken torsion or extension spring The opener is lifting the door's full weight, stalling the motor mid-travel. Look for a visible gap in the torsion spring above the door.
- Door out of balance or binding Worn rollers, bent track, or dry hinges add enough drag to stall the motor and drop RPM.
- RPM sensor harness loose A loose plug between the encoder and the logic board interrupts RPM pulses.
- Failed RPM/travel module Hall-effect sensor or encoder magnet failure — suspect this only after the door checks out mechanically.
Other parts sometimes needed
If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.
More LiftMaster garage door opener codes
Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician. Verified against manufacturer documentation: liftmaster.com.