How to clean robot vacuum sensors, and why navigation gets worse over time

Why your robot seems to get dumber over time

A new robot vacuum feels almost magical for the first few months. Clean straight lines, perfect docking, no bumping into the same chair leg. Then, slowly, things slip.

It starts missing edges. It thinks a dark rug is a cliff. It wanders off its rows or rotates in place trying to find the dock. Many owners assume the robot is wearing out or that a software update broke it.

Most of the time, the real cause is far more boring: dust, hair and smudges on sensors the robot uses to see. A robot vacuum lives at floor level in the dustiest part of your home, and its sensors get the full exposure.

In this guide, I explain which sensors your robot has, what each one does when it gets dirty, how manufacturers say to clean them, and the other wear issues that make navigation worse over time.

Flagship robots like the Qrevo Edge 3 Pro carry a dozen or more sensors, and each one needs an occasional wipe to stay accurate. Read my Roborock Qrevo Edge 3 Pro review →

The sensors your robot uses to see, and what dirt does to them

Most modern robots carry the same core set of sensors. Roborock's S7 manual, for example, lists a dock locator, a wall sensor, a carpet sensor and six cliff sensors as the parts to wipe during routine maintenance.

Here is what each sensor does, where it usually sits, and what goes wrong when it gets dirty.

Not every robot has every sensor. Budget gyro robots may skip LiDAR and cameras; flagships often add extra ones. Your manual's diagram is the best map of what to clean.

Mid-range robots like the Qrevo S Pro combine LiDAR on top with cliff, wall and carpet sensors underneath. Read my Roborock Qrevo S Pro review →

What manufacturers say to clean sensors with

The single most consistent instruction across brands is simple: use a soft, dry cloth.

iRobot's cliff sensor guide says to wipe all cliff sensor openings with a clean, dry microfiber or soft cotton cloth. Roborock's manuals say the same for all sensors. Dreame's cliff sensor guide goes further and says not to use wet wipes, rubbing alcohol or harsh household cleaners.

One of Dreame's own user manuals warns that wet cloths can damage sensitive elements in the robot and dock and tells owners to use dry rags.

There is one common exception. For the top-mounted camera on some older Roombas, iRobot's maintenance article suggests a microfiber or cotton cloth lightly dampened with water or screen cleaning solution. Follow your own model's instructions for camera windows.

My kit

A clean microfiber cloth, a few cotton swabs for tight corners and a soft paintbrush for the LiDAR turret vents. That is all I use.

Robots like the L40 Ultra Gen 2 have several clear sensor windows underneath that collect dust from every run. Read my Dreame L40 Ultra Gen 2 review →

Cliff sensors: the cause of most strange behavior

Cliff sensors deserve special attention, because they cause the most confusing problems when dirty.

iRobot lists dirty cliff sensors as one of the main causes of its Error 6, alongside driving over a dark surface or getting stuck over an actual edge. That combination is why so many owners see the robot refuse to cross a black or navy rug: a dark surface reflects less infrared light, and a dusty sensor makes the reading even weaker.

Camera-based navigation has its own version. iRobot's Error 17 guide for camera-equipped models says to keep the camera clear of dust and to make sure rooms have at least dim light, because extremely dark rooms can obscure the localization camera.

Quick test: On many robots you can cover one cliff sensor with a finger while the robot is running on a flat floor; it should react as if it found a drop. If one sensor never reacts after cleaning, contact support.

Budget robots like the Q10 S5+ rely on the same infrared cliff sensors as flagships, so a monthly wipe matters just as much. Read my Roborock Q10 S5+ review →

Other reasons navigation gets worse over time

Dirty sensors are the biggest cause, but not the only one. These are the other reasons I see navigation slowly get worse.

Wheel slip is the sneaky one. Robots use wheel rotation, plus a gyroscope, to estimate movement between LiDAR or camera updates. Hair wound around an axle makes the wheel turn without the robot moving as far, and that small error adds up across a room.

The same manual warns against carrying the robot by the laser sensor cap, the top cover or the bumper. A turret that has been knocked or used as a handle is a common source of later LiDAR problems.

Self-emptying robots like the Shark AV2501S AI Ultra still need their wheels and caster cleared of hair to keep navigation accurate. Read my Shark AV2501S AI Ultra review →

My sensor cleaning schedule

Here is the cleaning schedule I follow. It is based on the brands' guidance, adjusted for a home with a shedding pet. Without pets, you can stretch most of these intervals.

The whole routine takes me about five minutes. I do it right after emptying the bin or changing a dock bag, so it piggybacks on a habit I already have.

Pair it with brush cleaning: I wipe sensors on the same day I clear hair from the main brush. The robot is already upside down on the counter, so it adds almost no time.

Simple vacuum-only robots like the Roomba 105 Vac still have cliff sensors and charging contacts that benefit from a regular wipe. Read my iRobot Roomba 105 Vac review →

When to reset, re-map or call support

Sometimes cleaning everything doesn't fix the problem. Here is how I decide between a reset, a re-map and a support call.

If the robot gets lost in specific rooms after furniture moved, I delete and rebuild the map. A clean map often fixes "navigation" problems that were really map problems.

If the robot behaves oddly right after a firmware update, I check the brand's app or support page for known issues and make sure the update finished installing. A full power-off and restart helps more often than you would expect.

If one specific sensor keeps throwing errors even when it is spotless, or the LiDAR turret makes grinding noises or stops spinning, that is a hardware problem. Under warranty, contact support before opening anything.

Robots with advanced obstacle sensing, like the DEEBOT T90 PRO OMNI, also benefit from a fresh map after major furniture changes. Read my ECOVACS DEEBOT T90 PRO OMNI review →