Brake pads wearing thin and discs worn: what the MOT advisory means
"Brake pad(s) wearing thin" is an MOT advisory meaning the pads still work and passed the test, but they're getting close to the point where they need replacing. Book them in within the next month or two. Leave them much longer and they'll wear down to the metal backing plate and chew into the discs, which roughly doubles the cost of the job.
"Brake disc worn, pitted or scored" is the same kind of warning for the discs, the metal plates the pads grip.
When thin pads become an MOT fail
The MOT inspection manual has two pad lines that fail a car:
- Pads worn down to the wear indicator: a major defect, so it's a fail.
- Pads worn below 1.5mm of friction material: a dangerous defect. The car shouldn't be driven until it's fixed.
New pads typically start with something like 10mm to 12mm of friction material, so "wearing thin" usually means a few millimetres left. How long that lasts depends on how you drive. Town driving with lots of stop-start wears pads much faster than motorway miles.
Signs your pads are almost finished
- A high-pitched squeal when you brake. Many pads have a small metal tab that touches the disc when they're low, on purpose.
- A brake pad warning light on the dash. Cars with electronic wear sensors light up when the pad reaches the sensor.
- Grinding or scraping. That's metal on metal and needs doing straight away.
- The brake fluid level in the reservoir slowly dropping. As pads wear, the pistons move out and more fluid sits in the calipers.
What the disc advisory means
Discs wear too, just more slowly. A tester will advise on discs that are:
- Worn. You'll often feel a raised lip on the outer edge where the pad doesn't reach.
- Pitted. Rust has eaten small holes in the braking surface, common on cars that sit for weeks or do mostly short trips.
- Scored. Deep grooves, often from pads that went down to metal or from grit trapped between pad and disc.
Light surface rust after a wet night is normal and clears in the first few stops. It isn't what the tester is talking about. Once a disc is "significantly and obviously worn", the manual makes it a major defect.
Every disc has a minimum thickness stamped on it, often on the edge or the hub face. A garage measures with a micrometer and compares.
What it costs
BookMyGarage's figures (October 2026) put the average for front pads and discs at about £277 and rear pads and discs at about £246, with big swings by make and by area. Their Swansea average for rear pads and discs was among the cheapest at around £187. See their breakdown.
As a rough guide at an independent garage:
| Job | Typical price, parts and labour |
|---|---|
| Pads only, one axle | £90 to £180 |
| Pads and discs, front | £180 to £350 |
| Pads and discs, rear | £170 to £320 |
Pads are always replaced in axle sets, both sides together. Discs usually are too.
Can you do it yourself?
Pads on most older cars are a reasonable DIY job if you're handy with tools, have axle stands and a torque wrench, and know how to push a caliper piston back. Discs add a bit more work, especially if the retaining screws have seized.
Two cautions. Many newer cars have an electronic parking brake, and the rear calipers need putting into service mode with a scan tool before you can wind the pistons back. And brakes aren't the place to learn by trial and error. If you're not sure, pay someone.
What to do now
Only got the pads advisory? Get a quote for pads and ask the garage to measure the discs at the same time so you're not paying for labour twice next year. With several advisories, paste them all into the MOT advisory decoder to see the full picture.
Did the tester also mention corroded brake pipes or hoses? Read the corroded brake pipe guide. Those matter just as much as the pads.
Got more than one advisory?
Paste your whole MOT result into the decoder. It explains every line, sorts them by urgency and adds up a rough repair budget.
Decode my MOT