As a car owner, you're probably well aware of the importance of maintaining your vehicle to ensure it passes the annual MOT (Ministry of Transport) test. While most people focus on the obvious things like brakes, lights, and tires, one often overlooked aspect is the screen wash system. Yes, that's right — your car's screen wash can actually cause it to fail the MOT!
At ScreenWashKing, we've seen it all when it comes to screen wash issues. That's why we're here to share our expertise and help you understand why a good quality screen wash matters for your MOT and how to avoid failure.
The Importance of a Functioning Screen Wash
According to UK MOT guidelines, every vehicle must have a fully working windscreen washer system that sprays fluid effectively. If it doesn’t, it can be classed as a major defect, which means an instant MOT fail.
The screen wash system is a key part of your car’s visibility safety features. It helps clear dirt, grime, and road spray from your windscreen so you have a clear view of the road. During the MOT, the examiner will test the washer jets to ensure fluid sprays and cleans the windscreen properly.
If the windscreen wash doesn’t function as it should — or there’s no fluid at all — the examiner is required to fail the vehicle. Visibility is a core part of MOT safety standards.
Common Screen Wash Issues That Can Cause an MOT Failure
1. Adequate Fluid Supply: Low washer fluid levels are one of the simplest reasons for failure. If the reservoir is empty and the washers don’t work during the test, it results in an automatic fail.
2. Ineffective or low-quality screen wash: The screen wash fluid must be able to effectively clean the windscreen, removing any dirt, grime, or debris.
3. Blocked or Damaged Nozzles: Over time, the screen wash nozzles can become blocked or damaged, preventing the fluid from reaching the windscreen effectively.
4. Faulty Windscreen Washer Pump: If the screen wash pump is not working correctly, it won't be able to provide the necessary pressure to the system, leading to a failed MOT.
5. Leaks in the System: Any leaks in the hoses, connections, or other components of the screen wash system can cause a failure.
To avoid these issues and ensure your car passes its MOT, it's a good idea to have your screen wash system checked and serviced regularly. So, don't neglect your screen wash system — it could be the difference between a pass and a fail!
At ScreenWashKing, we offer high-performance car screen wash that are designed to keep your windscreen sparkling clean and ensure clear visibility all year round.
Common Windscreen Issues That Can Cause MOT Failures
Your windscreen is just as important when it comes to MOT visibility. Even minor issues can lead to a fail if they affect the driver’s view. Below are some common windscreen issues that could result in an MOT failure:
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Chips or cracks in the driver’s line of sight will result in a fail if they’re over 10mm in size. Cracks up to 40mm elsewhere can also be a problem.
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Smears, dirt, or poor visibility caused by ineffective screen wash or dirty wipers can lead to a visibility fail — even if the glass itself isn’t damaged.
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Worn wiper blades that leave streaks or don’t clear water properly also contribute to poor visibility, and that can be flagged during the test.
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Obstructed or tinted glass such as stickers, devices, or heavily tinted windows in the wrong place can block the tester’s view of the road, triggering a fail.
Keeping your windscreen well maintained, your car's screen wash topped up, and your wipers working properly is one of the easiest ways to avoid an MOT failure. Clean vision equals safe driving — which covers one of the most critical safety areas in the test.
So, Does Car Screen Wash Really Matter?
Absolutely — and especially when your MOT is coming up. Using plain water or a weak washer fluid might seem convenient, but it’s a shortcut that could cost you. If your washer system doesn’t spray, can’t clean the screen, your car could fail the test — or even be deemed unsafe if stopped by police.
Under UK regulations, a dirty windscreen that obstructs your view can be considered a road safety hazard. That’s why it’s important not just to use any car screen wash, but to choose one that’s built for UK conditions and performs year-round.
That’s where ScreenWashKing comes in. Our concentrated screen wash tablets are designed to do more than just clean — they keep your system protected and effective. Whether it’s rain, grit, bugs, bird droppings, or frost, our formula cuts through it all. Just one tablet makes up to five litres of high-performance windscreen wash that won’t freeze, won’t smear, and won’t block your system.
When visibility matters most, we’ve got your windscreen covered.