Chamberlain Garage Door 4-6 Blink Code — Fix

What Does This Error Mean?

Blink code 4-6 (four flashes, pause, six flashes) means the RPM sensor inside the motor has detected an unexpected speed change. The door usually reverses mid-travel. Causes include door binding, broken springs, or worn rollers — not the sensor itself.

How to Fix It

Disconnect the door from the opener using the red emergency release rope. Manually open and close the door by hand. It should move smoothly with light effort throughout its full travel.
If the door is heavy or sticks at any point, the springs may be broken or out of balance. Look at the torsion springs above the door — a gap or break in the coil means a spring has snapped. This is a job for a garage door technician (high-tension springs are dangerous).
Inspect the rollers (the wheels on the door that run in the tracks). Replace any roller that is worn, broken, or has a missing bearing. Lubricate all rollers with garage door spray lubricant — never WD-40.
Check the tracks for dents, debris, or screws sticking out. Straighten any bent track section and remove any obstructions.
After mechanical repairs, reconnect the door to the opener and test. If 4-6 returns and the door now moves smoothly by hand, adjust the force settings on the opener — the limit may be set too low for the current door weight.

Frequently Asked Questions

Is blink code 4-6 dangerous?

It is a safety feature working correctly — the opener detects the door is binding and stops to prevent damage or injury. However, the underlying mechanical issue (broken spring, worn rollers) needs fixing before continued use is safe.

Can I increase the force settings to overcome 4-6?

Only as a last resort, and only by small amounts. Increasing the force masks the underlying mechanical issue and creates a real safety hazard. A door that crushes vehicles or people because the force was set too high causes serious injury and major liability.

How much does it cost to fix the mechanical cause of 4-6?

A pair of torsion springs replaced by a technician typically costs £200-£400. A roller set is £30-£60 in parts plus 1 hour of labour. Worn cables run £40-£80 per side.