Will a Cracked Windscreen Fail an MOT?

The Short Answer: It Depends on Location and Size

A cracked windscreen does not automatically fail an MOT in every circumstance — however, it very often will. Furthermore, the rules are stricter than many drivers realise. Consequently, it is important to understand the specific criteria that MOT testers use to assess windscreen damage before your test.

The MOT rules divide the windscreen into zones, and the acceptable size of damage varies depending on which zone it falls in. As a result, a chip or crack that is perfectly legal in one position on the screen may cause an immediate failure just a few centimetres away.

Understanding the Windscreen Zones

The MOT inspection manual divides the windscreen into zones based on their importance to the driver’s field of vision. Understanding these zones is therefore essential to knowing whether your windscreen damage will cause a failure.

Zone A — The Critical Zone

Zone A is a 290mm wide band centred on the steering wheel, directly in the driver’s line of sight. This is the most critical area of the windscreen — any chip or crack larger than 10mm in Zone A is a category S defect and will result in an immediate MOT failure. Moreover, the rules are particularly strict here because damage in this zone can directly impair the driver’s ability to see the road clearly.

Zone B — The Rest of the Swept Area

Zone B covers the remainder of the area swept by the windscreen wipers. In this zone, damage up to 40mm is generally acceptable. However, if the damage causes significant distortion, discolouration, or obscures the driver’s vision, it can still result in a failure even if under 40mm.

Outside the Swept Area

Damage outside the wiper-swept area is generally considered less critical. However, the windscreen must still be in good condition and not so damaged that it poses a safety risk or compromises the structural integrity of the vehicle.

What Types of Damage Will Fail?

The following will result in an MOT failure in most cases:

• A chip or crack larger than 10mm in Zone A (the driver’s primary vision area)
• A chip or crack larger than 40mm anywhere in the swept area
• Damage that causes significant distortion in the driver’s line of sight, regardless of size
• A windscreen that is extensively cracked in multiple areas
• Damage that means the windscreen is not secure or at risk of collapsing

What About Advisory Items?

Smaller chips and cracks that do not meet the failure criteria may instead be recorded as advisory items on your MOT certificate. An advisory does not prevent you from passing the MOT, however it does indicate that the damage should be monitored and repaired soon. Furthermore, an advisory chip that is left untreated may spread to the point of becoming a failure item before your next test.

Can I Fix the Windscreen Before My MOT?

Absolutely — and we strongly recommend doing so. If your windscreen has any chip or crack that might be in the critical zone or is close to 40mm, book a repair before your MOT rather than risking a failure and a retest fee. In addition, fixing a chip before it spreads prevents a more expensive full replacement later.

A professional chip repair will restore the structural integrity and optical clarity of your windscreen, and in most cases the repaired area will not cause an MOT failure even in Zone A — provided the repair itself is clean and undistorted. However, if the original damage was too large to repair, a full replacement will be necessary before the test.

What Happens if I Drive with a Failed Windscreen?

If your vehicle fails its MOT due to windscreen damage and you continue to drive it, you are driving a vehicle that has been found not to meet the legal safety standards. Moreover, if stopped by police, you could face a fixed penalty notice and potential points on your licence. In addition, your insurance may be invalidated if you are involved in an accident while knowingly driving an unsafe vehicle.

Book a Repair Before Your MOT

If you are unsure whether your windscreen damage will cause an MOT failure, call us before your test. We can assess the damage over the phone, advise on whether a repair or replacement is needed, and in most cases attend the same day or the following morning. It is a far better use of your money than risking a failure and retest fee.