The short version
- 01Move the robot to a new location and press CLEAN to restart, as iRobot instructs.
- 02Turn it over and find the four cliff sensor windows along the front edge of the bumper.
- 03Wipe each sensor window with a clean dry cloth, and a melamine sponge if it is filmy.
- 04Note whether it always stops in the same place, which points at the floor not the robot.
- 05Test on a light-coloured floor to rule out a dark rug being read as a drop.
- 06Use a Virtual Wall to block off a genuinely problematic area.
Raw message
Error six (6). Move Roomba to a new location, then press CLEAN to restart. Drop off detected. Move to a new area, and then press Clean
Likely causes
- Dirty cliff sensors, which iRobot names first for the 600 series.
- The robot genuinely stuck, hanging over an edge or on a threshold.
- A dark surface, such as a black rug, that the sensors read as a drop.
- A constant cliff reading, which is how the i Series describes the same condition.
- Sensor windows scratched or clouded with age.
Three different situations, one code
iRobot's 600 series chart is the more revealing of the two here. The message is “Error six (6). Move Roomba to a new location, then press CLEAN to restart,” and the likely cause is given as a list: the cliff sensors are dirty, Roomba is stuck, hanging over a cliff, or is on a dark surface. Four possibilities, only one of which is an actual drop.
The i Series wording is “Drop off detected. Move to a new area, and then press Clean,” with the cause given as a constant cliff detected and the instruction to check that cliff sensors are clear of debris. Same condition, described from the sensor's point of view.
The cliff sensors are infrared emitters and detectors on the underside of the front bumper. They look at the floor continuously and expect a reflection back. Anything that stops the reflection returning — dust on the lens, a genuine drop, or a surface too dark to bounce enough light — reads identically to the robot.
Cleaning the sensors
Turn the robot over and look along the front edge of the bumper for the small recessed sensor windows. A dry cloth over each one takes seconds, and it resolves the most common version of this error. Dust films these lenses gradually, which is why the fault appears out of nowhere on a robot that has worked for a year.
Do this even if the sensors look clean. The film that defeats an infrared sensor is not necessarily one you can see, and wiping four small windows costs nothing compared with the alternative of chasing the problem around your floors.
If the windows are scratched or clouded rather than dirty, cleaning will not help and the reading will stay unreliable. That is a service question rather than a maintenance one.
When the floor is the problem
Pay attention to where it stops. A robot that reports this error in a different place each time usually has dirty sensors. One that stops reliably at the same dark rug, the same threshold or the same glossy patch is telling you about your floor, and no amount of cleaning will change that.
Dark surfaces are the classic case, and they are a genuine limitation rather than a defect: a very dark rug absorbs the infrared the sensor is looking for, so the robot concludes there is nothing beneath it and stops rather than risk a fall. Testing the same robot on a light floor separates that from a sensor fault in one run.
iRobot's own suggestion for an area that keeps causing problems is to use a Virtual Wall to block it off. That is a reasonable permanent answer for a threshold or a rug the robot will never read correctly.
Sources and review notes
Checked on . Based on iRobot's published error message charts for the Roomba 600 series and i Series. The explanation of how the infrared cliff sensors work, and the diagnostic of noting whether the robot stops in the same place, are editorial. Codes differ by series — check the chart for your own model. iRobot's support pages render only in a browser, so they cannot be checked by automated fetching. Glitchary is independent of iRobot.