Windscreen Chips, Wipers & Washers: The MOT Rules Explained

The Windscreen Zones That Matter

The windscreen is divided into zones for MOT purposes. The most important is the area directly in front of the driver, roughly the size of the swept area of the driver's side wiper blade — this is treated as the "primary vision area."

• Zone A (driver's primary vision area): any chip or crack larger than 10mm is an automatic failure
• Rest of the windscreen: damage is only a failure if it's larger than 40mm, or if it obstructs the driver's view generally

Multiple smaller chips can also cause a failure if the tester judges they combine to obstruct the driver's vision.

Can a Chip Be Repaired Instead of Replaced?

Often, yes. A small chip caught early, especially outside the direct line of sight, can usually be repaired rather than requiring a full windscreen replacement, which is both cheaper and quicker. It's worth getting any chip looked at as soon as you notice it, since they tend to spread — especially in cold weather or after a pothole impact.

Wipers

Testers check that both the front and, where fitted, rear wipers clear the screen effectively without smearing, streaking or leaving unwiped patches. Common issues include:

• Perished or split rubber blades that judder or skip
• Wiper arms that don't return properly or have insufficient spring tension
• Wiper motors that don't operate at all speeds

Wiper blades are inexpensive and simple to replace — if yours are more than a year or two old, or you've noticed streaking, it's worth swapping them before your test.

Washer Fluid

An empty washer bottle is one of the most common — and most avoidable — reasons for an MOT to fail unnecessarily. Testers check that washer jets spray fluid onto the screen effectively. Top up your washer fluid the night before your test, and check the jets aren't blocked or misaligned.

Rear Windows and Visibility

While the MOT doesn't check the rear window as strictly as the windscreen, mirrors need to be secure, undamaged, and positioned to give the driver a clear rearward view — worth checking alongside your windscreen and wipers.

For the rest of the pre-test essentials, see our complete pre-MOT checklist.