Can you fail an MOT for no screenwash?

Yes, and it is one of the easiest failures to avoid. The tester checks that the washers deliver enough liquid to clear the windscreen in conjunction with the wipers, and a car with an empty bottle cannot demonstrate that. It is recorded as a defect under the driver's view of the road, alongside worn wiper blades, damaged glass and anything obstructing the swept area. Filling the bottle before you go costs nothing and takes two minutes.

Can I use water instead of screenwash?

You can in an emergency, but not as a habit. Water freezes, and a frozen reservoir can split the bottle, the hoses or the pump — a far bigger job than buying screenwash. It also does almost nothing against the film of salt, oil and diesel spray that builds up in winter, which is precisely when you need the washers most, and standing water in a warm engine bay is a breeding ground for bacteria. Proper screenwash contains detergent and antifreeze and is inexpensive.

Is it illegal to drive without working windscreen washers?

Yes. The construction and use regulations require windscreen washers and wipers to be fitted and in efficient working order on cars that need them, and that applies every day you use the vehicle, not just on the day of the MOT. An empty bottle means the washers are not in working order. In practice it is rarely the reason anyone gets stopped, but it becomes very relevant if your view of the road is poor and something happens as a result.

Why is my washer fluid light on when the bottle is full?

Almost always the float switch in the reservoir, which sticks or fails and reports low regardless of the actual level. It is a cheap part but often awkward to reach, since the bottle usually has to come out from behind the wheel arch liner. Before assuming that, check the level yourself rather than trusting the last top-up: a cracked bottle or a detached hose empties quietly, and a car with headlamp washers gets through a surprising amount.

Dashboard warning light

Washer fluid warning light

Last updated 27 July 2026

Quick answer

The washer bottle is low or empty. It is the most trivial warning on the dashboard and one of the few that maps straight onto a real MOT failure, because the washers and wipers are both tested and an empty bottle means the washers cannot do their job.

What to do: Book it in, not urgent
Can you drive?: Yes

Why it is amber

A system has reported a malfunction, or something needs attention. The car is usually still driveable, but the fault will not clear itself and several amber lamps are an automatic MOT failure.

What turns it on

A float switch in the washer reservoir closes when the level drops past a set point. On cars with headlamp washers the same bottle usually feeds both, and headlamp washers empty it remarkably quickly, which is why the lamp sometimes appears within days of filling it in winter.

What to do about it

Top it up with proper screenwash, mixed to the strength on the bottle for the time of year. It is a two-minute job on the driveway and needs no tools.
Do not use plain water. It freezes and splits the bottle, pump or hoses, it does not shift the greasy road film that makes a screen unreadable into low sun, and standing water in a warm engine bay is a place bacteria grow.
Check it before the MOT. An empty bottle is one of the most avoidable failures there is, and testers see it constantly.
If the jets deliver nothing after topping up, check the jets themselves for blockage — a pin clears them — and listen for the pump running when you pull the stalk. Silence points at the pump or its fuse.
If the level keeps dropping without you using it, look for a split bottle or a perished hose. Washer bottles crack low down after a hard frost and empty themselves quietly.
Check the wiper blades at the same time. Washers and wipers are tested together, and smearing or juddering blades fail as readily as a dry bottle.

Can you keep driving?

Yes

Yes, but not indefinitely, and not only because of the MOT. Using a vehicle on the road with washers or wipers that do not work is an offence in its own right under the construction and use regulations, quite separately from the annual test. More to the point, a windscreen filmed with salt and diesel spray becomes almost opaque against low winter sun, and no amount of wiping clears it dry.

What causes it

The bottle simply needs filling, which is nearly always the answer
A cracked reservoir or a split, perished or detached hose, usually after a frost
Heavy use of headlamp washers, which share the same bottle and empty it fast
Frozen fluid because plain water or an over-diluted mix was used
A failed washer pump or a blown fuse, where the level is fine but nothing comes out
Blocked or misaimed jets, often blocked by wax after a car wash
A failed level sensor, which leaves the lamp on with a full bottle

Does it fail an MOT?

Not on its own — but what causes it often does.

The lamp is not itself a listed defect, but what it causes is. The tester checks that the windscreen washer provides enough liquid to clear the screen when used with the wipers, and an empty bottle fails that check outright. The wipers are examined in the same section and are failed if they do not clear the screen effectively, so worn or smearing blades come with it. Both are recorded as defects under the driver's view of the road, which is one of the most commonly failed sections of the whole test and almost entirely preventable in a car park five minutes before the appointment.

Common questions

Can you fail an MOT for no screenwash?: Yes, and it is one of the easiest failures to avoid. The tester checks that the washers deliver enough liquid to clear the windscreen in conjunction with the wipers, and a car with an empty bottle cannot demonstrate that. It is recorded as a defect under the driver's view of the road, alongside worn wiper blades, damaged glass and anything obstructing the swept area. Filling the bottle before you go costs nothing and takes two minutes.
Can I use water instead of screenwash?: You can in an emergency, but not as a habit. Water freezes, and a frozen reservoir can split the bottle, the hoses or the pump — a far bigger job than buying screenwash. It also does almost nothing against the film of salt, oil and diesel spray that builds up in winter, which is precisely when you need the washers most, and standing water in a warm engine bay is a breeding ground for bacteria. Proper screenwash contains detergent and antifreeze and is inexpensive.
Is it illegal to drive without working windscreen washers?: Yes. The construction and use regulations require windscreen washers and wipers to be fitted and in efficient working order on cars that need them, and that applies every day you use the vehicle, not just on the day of the MOT. An empty bottle means the washers are not in working order. In practice it is rarely the reason anyone gets stopped, but it becomes very relevant if your view of the road is poor and something happens as a result.
Why is my washer fluid light on when the bottle is full?: Almost always the float switch in the reservoir, which sticks or fails and reports low regardless of the actual level. It is a cheap part but often awkward to reach, since the bottle usually has to come out from behind the wheel arch liner. Before assuming that, check the level yourself rather than trusting the last top-up: a cracked bottle or a detached hose empties quietly, and a car with headlamp washers gets through a surprising amount.

This is general guidance, not a diagnosis. Manufacturers draw the same system differently and reuse symbols for more than one function, so check the handbook for your own car before acting on anything here.

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