Start with the exact model and the complete wording shown in the app or spoken by the robot. A charging error and a cleaning error can share a number but describe different systems. Do not choose a replacement part from the number alone.
Roborock Q Revo: steady red dock light
A steady red status light on the Empty Wash Fill Dock
Signal type: dock light, not a numbered robot error. Roborock lists several possible conditions for the original Q Revo: a dock voltage error, the clean-water tank needing refill or reseating, the dirty-water tank needing emptying or reseating, or the cleaning tank/filter not installed correctly. The light alone does not identify which one applies.
Read the exact voice or app message. With the dock unplugged, check that the accessible tanks and removable cleaning tank/filter are seated, and refill or empty them as appropriate. Do not open the dock or test mains wiring. If the warning remains or the power rating does not match your location, stop and contact Roborock support. See Roborock’s Q Revo dock-light guidance and guided Q Revo checks.
Roborock S8: red flashing robot light with a voice alert
Robot error signal, not a diagnosis by color
For the standard S8, the manual says that the robot’s power indicator flashes red and a voice alert sounds when an error occurs. Record the full spoken or app message before choosing a check; the red flash alone does not identify a failed brush, sensor, battery or dock.
Follow the S8 user manual’s error guidance and the exact app prompt. If you have an observed cleaning or charging symptom without a clear alert, start the S8 diagnostic questions. Stop using damaged electrical equipment.
Roomba j series: charging errors
iRobot’s official charging error chart includes the j series. The wording and display can vary between the robot and app. The entries below are charging errors, not general cleaning errors. For a j7 that will not charge without a specific code, use the Roomba j7 charging diagnostic.
Charging Error 1 — battery detection
The robot does not detect its battery. Check the exact message in the iRobot app and follow the model’s official battery reseating instructions. Do not open a damaged or swollen battery.
Charging Error 2 — charging fault
Check for signs of liquid damage and confirm the battery is an authentic compatible iRobot unit. Stop if moisture or physical damage is present.
Charging Error 3 — charging system
Retry charging once as directed by iRobot and inspect for liquid damage. If it recurs, contact support instead of opening the dock.
Charging Errors 4 and 5 — no or low charging current
Disconnect the base from power and clean only the accessible charging contacts as directed by iRobot; then reseat the robot.
Charging Errors 6 and 7 — battery too hot or too cold
Let the robot return to room temperature before trying again. Do not heat or chill the battery to force a charge.
Charging Error 8 — battery communication
Check the app’s exact message and the official battery guidance. Do not assume a generic replacement battery will be compatible.
Charging Error 9 — battery fault
iRobot identifies a battery failure condition. Follow its model-specific guidance or contact support; do not continue charging a damaged battery.
Charging Error 11 — battery hardware fault
Follow iRobot’s model-aware guidance for a battery reset and reboot; contact support if it persists. Do not open or charge a damaged battery.
Charging Error 17 — battery authenticity
Confirm the installed battery is an authentic iRobot unit. Follow the official reboot guidance; contact support if the alert remains with an authentic battery.
Charging Error 19 — charging timeout
Check the dock power connection, then unplug the base and clean accessible contacts. iRobot’s detailed steps describe further battery checks. Stop if contacts are physically damaged.
Charging Error 20 — battery fault
Confirm an authentic battery and follow iRobot’s battery reseating guidance. Contact support if the fault persists.
Charging Error 21 — docked but not charging
Inspect and clean accessible charging contacts with the dock unplugged, then test again.
Important distinction: “Error 1” while cleaning can refer to a wheel or an uneven surface; it is not the same as “Charging Error 1.” Cleaning Error 5 (side wheel) also differs from Charging Error 5 (charging current). See iRobot’s cleaning Error 1 explanation.
Roomba j7: Error 5 while cleaning
Cleaning Error 5 — side wheel cannot turn
This is a cleaning error, not Charging Error 5. iRobot identifies a blocked side wheel: with the robot switched off, inspect both wheels for accessible debris, push them gently up and down, and compare how freely they turn by hand. Do not force a wheel that binds. If the message returns on a clear, level floor, stop and seek model-specific service advice.
See iRobot’s Error 5 instructions, the Roomba j7 wheel and sensor guide, or start guided movement checks.
Ecovacs DEEBOT T20 OMNI: cleaning sink or waste tank alert
Water remains in the cleaning sink, or a full-tank alert appears when it is empty
First distinguish water that actually remains in the sink from an alert with a dry sink. For the T20 OMNI, ECOVACS advises checking the waste tank sealing plugs and seating, then inspecting the accessible sink suction opening for debris. If the sink is dry but the alert persists, inspect and clean the accessible level-sensing surfaces with the station powered off. Do not add water to a sink that is already backing up or open the powered station housing.
See the official T20 OMNI support steps, the T20 OMNI dirty-water guide, or start guided water-recovery checks.
Dreame X40 Ultra: voice alert
“Laser sensor abnormal” / “LDS abnormal”
Signal type: voice prompt. System: laser navigation. Dreame lists this wording in its X40 Ultra FAQ and advises checking for an obstruction. Switch the robot off before inspecting the accessible sensor area; do not force or open the sensor assembly. If the message persists after an unobstructed restart, contact Dreame support. For movement without this alert, begin with the X40 Ultra model hub and match the observed symptom.
How to use this reference
- Confirm the model on its label or in its companion app.
- Record the complete code, voice prompt, app message, or light pattern and when it appears.
- Match both the signal type and the model before doing the safe first check.
- Stop if a mains cable, dock, or lithium battery is damaged, or if the next step requires opening powered equipment.
This reference does not imply that a named component has failed or that parts from another model are compatible. Official sources for the entries above were checked on 3 October 2026; follow the linked manufacturer guidance if it changes.