Craftsman Garage Opener Blink 4-6 — Photo Eye Alignment

What Does This Error Mean?

Blink 4-6 means the photo eye sensors aren't aligned — the safety beam between them is broken.
Each sensor has an LED that should glow steady when the beam is intact.
Loosen the wing nuts on the brackets, aim each sensor at the other, tighten.
Two minutes of work and blink 4-6 clears.
The door refuses to close until the photo eyes are aligned.

Affected Models

Craftsman 1/2 HP
Craftsman 3/4 HP belt drive
Craftsman chain drive
Craftsman Smart opener

Common Causes

Sensor knocked out of alignment by impact
Bracket loose, allowing sensor to droop
Lens dirty or cobwebbed
Sun directly on a lens (false beam break)
Photo eye wiring damaged

How to Fix It

Look at both photo eye LEDs.

Each sensor has an LED on its front.
Both should glow solid when alignment is good.
If one is off, dim, or flashing, that sensor is misaligned.
Most cases are just one out of alignment, not both.
Loosen the wing nut on each bracket.

The sensor mounts on a small adjustable bracket with a wing nut.
Loosen each wing nut by hand — don't use tools.
The sensor should swing freely up/down/left/right after the nut is loose.
Align by eye, then fine-tune by LED.

Aim each sensor straight at the other across the door opening.
Watch both LEDs as you fine-tune.
When alignment is right, both LEDs go solid steady.
If one flickers, you're close — wiggle the sensor slightly until it stops flickering.
Tighten the wing nuts.

Once both LEDs are solid, tighten the wing nuts firmly by hand.
Hand-tight is correct — don't use tools to crank them down, the brackets are flexible plastic and will crack.
Test the door close button to confirm blink 4-6 has cleared.
Clean the lenses if alignment looks correct.

If both LEDs are solid but the door still refuses to close, wipe each lens with a soft dry cloth.
Dust and cobwebs can dim the beam without breaking it visibly.
Especially common in garages used infrequently or in dusty environments.

Frequently Asked Questions

Why do photo eyes get misaligned?

Most often a person or pet bumps into one and the bracket flexes.
Other causes: vibration from the door slamming over years, the wood the bracket mounts to swelling/shrinking with seasons, or someone parking too close and brushing the sensor.
Quick re-alignment is usually all that's needed.

Why doesn't sunlight cause photo eye issues every day?

Photo eyes use modulated infrared, so most ambient light is filtered out.
The exception is bright direct sun shining straight into the receiver — that overwhelms the IR filter.
If your garage faces east or west, you may see blink 4-6 only at certain times of day.
A small sun shield above the affected sensor solves it.