When the robot stops mid-cycle and the lights flash

A robot that quits halfway and flashes at you is protecting itself. It saw something it didn't like, and it chose to stop rather than keep going.

So the question isn't "what broke?" Usually it's "what did the robot notice?" The lights are the answer, in the maker's own code.

Safety mode, in plain terms

One maker's support page describes safety mode as an automatic shutdown triggered by the robot to protect its components¹. Not every maker uses that name. The idea is common.

The same page lists the usual triggers: a saturated filter, motor overheating, water temperature outside the operating range, or a blockage in the tracks¹.

The usual reasons for a stop

Full filter. The most likely suspect. When the filter is saturated, suction drops and many robots stop on their own¹. There's more on clearing the filter.

Heat. Some robots stop automatically when the safety temperature is exceeded. That page says to wait 15 to 20 minutes for it to cool down before restarting¹. It also suggests placing the transformer in a well-ventilated area, out of direct sunlight¹.

Out of water. Some makers list "out of water" as a signal, and your manual says what triggers it. One troubleshooting list for a power-supply blink starts with checking whether the unit is out of water². A cordless maker shows a flashing purple light as "Out of Water: Cleaning Mode Changed"³.

Stuck. The same cordless maker shows solid purple as "Device is stuck"³. A robot caught on a ladder, a step or a drain cover can stop here.

Battery. On a cordless robot, a low battery can show as a blink. A maker's troubleshooting page ties a blinking indicator, in intervals or at 1 second, to a battery that's running out⁴.

Motor or power. Tracks, brushes, or a power problem. Those have their own pages, on drive faults and power faults.

What to write down before you touch it

It takes half a minute and it helps whoever you call later. One maker asks for the indicator light, the point of shutdown and the cycle duration before stopping, when you contact after-sales support¹.

So note:

• The light color and pattern.
• Where in the pool the robot stopped, and how long it had run.
• Whether the filter looked full.
• Whether the robot or power supply felt warm.

Getting it going again

Power it off and lift the robot out before you check anything, as your manual says. The page on what to do first covers power and water.

Once the cause is cleared, restart the way your manual says. One example: a troubleshooting list says to press the power button once, and the cleaning program will resume from where it left off². That's for one robot. Others start over, so follow your own manual.

When it keeps happening

If a robot stops again and again after you've cleared the obvious causes, don't keep restarting it. Note the pattern and contact the maker's support with your model and serial number. If you need the manual, there's a page on finding it.