Chamberlain · Garage Door Opener Moderate

3-1 — RPM sensor / motor not detected

The logic board is not receiving RPM feedback from the motor. The motor may be unplugged, the harness damaged, or the motor itself failed.

Keep using it?
Yes, with caution
DIY difficulty
Moderate
Verified against
chamberlain.com ↗

How to fix it

  1. Unplug the opener.
  2. Remove the light lens and logic board cover.
  3. Re-seat all connectors on the logic board, especially the motor harness.
  4. Restore power and test. If 3-1 persists, the motor or board needs replacement — contact Chamberlain support or a service tech.

Why it happens

Typical signs: 3 flashes then 1 flash · Motor hums but trolley does not move, or motor does not run at all · Door will not open or close

  • RPM/motor harness unplugged Connector worked loose from the logic board.
  • Failed RPM sensor Hall-effect sensor on the motor failed.
  • Failed motor Motor brushes worn or windings open.
  • Failed logic board Board no longer reads RPM input.

Parts you may need

If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.

  • Chamberlain logic board Common replacement
    Amazon →

More Chamberlain garage door opener codes

1-1 1-1 — Safety Sensors Obstructed/Misaligned/Disconnected 1-2 1-2 — Safety Sensor Wires Shorted or Reversed 1-3 1-3 — Door control wire issue / lock button stuck 1-4 1-4 — Safety sensors misaligned or obstructed 1-5 1-5 — Motor Drive / No RPM at Start of Movement 1-6 1-6 — Unexpected RPM After Stop at Open Position

All Chamberlain codes → All 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: chamberlain.com.