LiftMaster 041C4398A RPM Sensor Kit – 5-Blade Motor Speed Sensor

The LiftMaster 041C4398A is a genuine replacement RPM sensor kit for compatible LiftMaster and Chamberlain residential garage door openers.

The RPM sensor monitors how quickly the opener motor shaft is rotating. It works with a 5-blade interrupter cup that spins through the optical sensor as the motor operates, allowing the opener's control board to monitor motor movement and speed.

A failed RPM sensor can cause an opener to start moving and then stop or reverse after only a short distance because the control board is no longer receiving the expected motor-rotation signal.

### Product Features

- Genuine LiftMaster / Chamberlain replacement part
- Current part number 041C4398A
- Replaces older 41C4398-series RPM sensors
- 5-blade photo-interrupter sensor system
- Monitors garage door opener motor-shaft rotation
- Provides motor-speed feedback to the logic board
- Compatible with select LiftMaster and Chamberlain AC openers
- Used on compatible chain-drive and belt-drive models
- No remote or keypad programming required after replacement

### Specifications

- Manufacturer: LiftMaster / Chamberlain
- Part Number: 041C4398A
- Previous Part Number: 41C4398
- Product Type: RPM Sensor Kit
- Sensor Type: Optical Photo Interrupter
- Interrupter Style: 5 Blade
- Application: Residential Garage Door Opener
- Installation Location: Inside Opener Powerhead
- Function: Motor RPM / Rotation Feedback

### What Does the RPM Sensor Do?

The RPM sensor allows the opener's control electronics to confirm that the motor is actually rotating when power is applied.

During operation:

Motor Shaft → Interrupter Cup → RPM Sensor → Logic Board

As the interrupter cup rotates through the optical sensor, the sensor generates pulses that the logic board uses to monitor motor movement.

If those pulses disappear or become inconsistent, the opener may interpret the condition as a motor or travel problem and stop operation.

### Common Symptoms of a Failed RPM Sensor

A faulty RPM sensor may cause:

- Opener starts and stops after only a few inches
- Door begins moving and unexpectedly reverses
- Motor runs briefly and then shuts off
- Intermittent opener operation
- Motor rotation is not recognized by the logic board
- Door will not complete a full opening or closing cycle

These symptoms can also be caused by:

- Damaged interrupter cup
- Failed logic board
- Motor problems
- Wiring problems
- Worn gears
- Binding or improperly balanced garage door

Proper diagnosis is recommended before replacing electronic components.

### Replacement / Cross-Reference Numbers

LiftMaster lists this kit under or as a replacement for:

- 041C4398A
- 41C4398A
- 41C4398
- 41C4398-1
- 41C3005
- 41B3000
- 1A4903
- K75-16426

If your existing sensor carries one of these numbers, verify your opener model before ordering.

### Compatibility

The 041C4398A is used with numerous compatible LiftMaster and Chamberlain garage door openers manufactured after 1997.

Compatible applications include select models such as:

- LiftMaster 1240 / 1240R
- LiftMaster 1245 / 1245R
- LiftMaster 1246
- LiftMaster 1255
- LiftMaster 1265
- LiftMaster 1345
- LiftMaster 1346
- LiftMaster 2265
- LiftMaster 2280
- LiftMaster 3265
- LiftMaster 3280
- Chamberlain CG40 / CG40CD
- Chamberlain PD210 / PD212
- Chamberlain HD200D
- Chamberlain LW3000
- Select additional compatible LiftMaster and Chamberlain openers

Compatibility varies by production date and opener configuration.

Always verify the owner's manual, replacement-parts diagram, opener model, and original sensor number before ordering.

### Important Compatibility Note

This RPM sensor is not universal across all LiftMaster garage door openers.

Newer DC-powered openers and other drive-system designs may use a travel module, encoder, or different motor-position sensing system instead.

Do not order based solely on the LiftMaster brand.

### Package Contents

Includes:

- 1 – LiftMaster 041C4398A RPM Sensor Assembly
- 1 – 5-Blade Interrupter Cup

Garage door opener, motor, logic board, wiring harness, and other internal components are not included.

### Important Installation Note

Disconnect the garage door opener from electrical power before removing the powerhead cover or servicing internal components.

During installation:

- Verify the interrupter cup is properly positioned on the motor shaft
- Make sure the blades pass cleanly through the optical sensor
- Check the sensor wiring connection
- Inspect the old interrupter cup for cracking or distortion
- Keep wiring clear of moving motor and gear components

After installation, operate the opener through several complete cycles and confirm normal opening, closing, and safety-reversal operation.