My window-cleaning robot leaves streaks after every pass
Home Nura guide — category Window Cleaning Robots
Diagnosis
A window-cleaning robot that leaves streaks nearly always has a dirty or worn pad, or the wrong amount of cleaning liquid. Streaks appear when dirt is just moved around and the water dries too fast, especially on warm or very hard-water-stained glass.
Possible causes
- Dirty or worn pad — it no longer holds onto grime and redeposits it as fine lines on every pass.
- Too much water or cleaner — the excess runs down, dries in drops and leaves rings or runs along the bottom of the glass.
- Glass in direct sun — the liquid dries before it is wiped and leaves white streaks of limescale or soap.
- Very dirty glass or a greasy film — one pass is not enough and the dirt is spread out without being absorbed.
Recommended procedure
- 1Remove the pad, hand-wash it in warm soapy water without fabric softener, rinse it well and let it dry before refitting.
- 2Wipe the frame and ledges with a damp cloth first, so the robot does not smear dust and grit across the glass.
- 3Clean windows in the shade or on an overcast day, and spray a moderate amount of the manufacturer's recommended cleaner.
- 4For very dirty or greasy glass, do a first cycle with little cleaner, then a second with a clean pad.
- 5Rinse the drive track and suction seal with clear water, and check the pad is held taut by its fixings.
Repair or replace?
If streaks persist with a new pad and a suitable cleaner, check the suction and the condition of the seal. A robot that keeps losing power or has a warped seal is rarely worth repairing and is better replaced.
Other common failures on this category
These incidents affect the same type of appliance — diagnosis and recommended procedure for each.
- Window Cleaning RobotsMy window-cleaning robot keeps losing grip and nearly falls
- Window Cleaning RobotsMy window-cleaning robot beeps non-stop and reports low suction
- Window Cleaning RobotsMy window-cleaning robot leaves a streak in the centre of the glass every pass
- Window Cleaning RobotsThe suction pad on my window-cleaning robot is losing grip and the unit slides
Frequently asked questions
In Europe, any window cleaning robots bought new from an official reseller benefits from a legal conformity guarantee of at least two years (Directive (EU) 2019/771). This guarantee covers defects present at delivery, whenever they first manifest.
You can pick: European law puts the legal guarantee on the seller, not the manufacturer. In practice, a store return is usually faster, but the manufacturer can repair if the damage is out of warranty. Keep proof of purchase.
Our public methodology adds a Nura Score /10 penalty to any window cleaning robots whose recurring failures are documented in European user feedback. A model that breaks too often never tops our charts, brand notwithstanding.
Yes, within the limits of the European "right to repair": routine maintenance tasks (cleaning, gasket replacement, calibration) never void the legal warranty. Only irreversible hardware modifications can be a problem. For a window cleaning robots, any handling documented in the manufacturer's manual stays covered.
The directive imposes a two-year legal conformity guarantee, with a presumption of pre-existing defect during the first twelve months — the burden of proof is on the seller. For a window cleaning robots that breaks in that window, you're entitled to free repair or replacement, no strings attached on typical use.