What Does A Failed Mot Mean When Buying — Dave's Complete Guide
A failed MOT does not always mean a bad car. Here's how to interpret MOT failures, which ones to worry about, and how to use them to your advantage.
Failed MOT: Disaster or Opportunity?
When most buyers see the words "MOT failure" attached to a Used Car, they run a mile. And I understand why. It sounds bad. It implies the car is broken, unsafe, or not worth buying.
But here is what experienced buyers know: an MOT failure does not always mean a bad car. Sometimes it means a very good car at a very good price, because the failure has scared off all the competition and the seller is desperate to get rid of it.
The trick is knowing the difference between a failure that is a cheap, quick fix and one that is a genuine deal-breaker. That is exactly what this guide is going to teach you.
Understanding the MOT Test
The MOT test is an annual safety inspection required for all cars over three years old in the UK. It checks that the car meets minimum safety and environmental standards for road use. The test covers areas including:
- Lighting and signalling equipment
- Steering and suspension
- Brakes
- Tyres and wheels
- Seat belts
- Body and structure
- Exhaust emissions
- Driver's view of the road
- Registration plates
- Vehicle identification numbers
If any item fails to meet the minimum standard, the car fails the test and is given a list of failure items that must be repaired before a retest. The car also receives advisories, which are items that are not yet at the failure point but are close to needing attention.
If you are weighing up alternatives, our guide to Outstanding Finance On A Used Car covers similar ground from a different angle.
How To Access the MOT history
Every MOT test result since 2005 is recorded online and available for free on the government website. Enter the registration number and you get the complete history, including all passes, failures, advisories, and mileage readings.
When you are looking at a car with a failed MOT, pull up the full history and look at what specifically caused the failure. This tells you everything you need to know about whether it is worth pursuing.
Failure Categories: Minor, Major, and Dangerous
Since May 2018, MOT failures have been categorised as either Major or Dangerous.
Dangerous defects are faults that pose a direct risk to road safety and mean the car should not be driven until repaired. Examples include a tyre with cord showing through the rubber, a structural member so corroded it has lost its integrity, or a brake component that has seized completely.
Major defects are faults that affect the vehicle's safety, the environment, or put other road users at risk, but are not an immediate danger. Examples include a headlight not working, emissions above the legal limit, or excessive play in a steering component.
Cheap Fixes That Cause MOT Failures
These are the failures that create buying opportunities. They sound bad on paper but cost very little to put right.
Blown Bulbs
A single blown headlight or tail light bulb will cause an MOT failure. The fix costs £5 to £15 and takes five minutes. If a car has failed solely because of a lighting issue, this is a non-issue.
For more on this topic, take a look at our How to Insure a Used Car Before Collecting It guide.
Wiper Blades
Worn or split wiper blades that do not clear the windscreen effectively will fail the MOT. New blades cost £10 to £25 and can be fitted in the car park.
Number Plate Issues
A cracked, faded, or incorrectly spaced number plate can cause a failure. Replacement plates cost £15 to £25 and are made while you wait.
Minor Tyre Issues
A tyre at 1.5mm tread depth will fail but a new budget tyre costs £40 to £80. Even a premium tyre is only £80 to £150. If the rest of the car is sound, this is a cheap fix.
Windscreen Chips
A chip in the driver's direct line of sight larger than 10mm will fail the MOT. A professional chip repair costs £30 to £50. A full windscreen replacement costs £150 to £400 depending on the vehicle.
You might also find our What Is an HPI Check and Do You Need One? guide useful alongside this one.
Moderate Fixes: Worth Considering
These failures cost more to fix but are still within the range where the car could be a good buy at the right price.
Brake Components
Worn brake pads are a common failure. Front pads typically cost £80 to £150 fitted. Front discs and pads together cost £200 to £350. Rear brakes are usually similar or slightly less. This is routine maintenance rather than a sign of a problem.
Suspension Wear
Worn shock absorbers, ball joints, or anti-roll bar drop links are common on cars over five years old. Individual components cost £50 to £200 each to replace fitted. If the MOT failure lists one or two suspension items, that is normal wear and tear.
Exhaust Issues
A corroded exhaust section or a blown silencer is a common failure on older cars. A rear section replacement costs £100 to £250 fitted. A full exhaust system replacement is more, typically £300 to £600, but it is still a known cost.
We have covered related ground in our How to Insure a Used Car Before Collecting guide, which is worth reading if this subject interests you.
Emissions Failure
A diesel car failing on emissions could be a simple fix (a good run at motorway speed to clear the DPF) or a more expensive one (DPF replacement at £800 to £2,000). Petrol cars failing emissions may need a new catalytic converter, which costs £200 to £800. Ask a mechanic before committing.
Deal-Breaker Failures
These are the failures that should make you walk away, or at least approach with extreme caution.
Structural Corrosion
If the MOT failure mentions corrosion to structural members, chassis legs, subframe mounting points, or suspension mounting points, be very careful. Structural rust repairs are expensive (£500 to £2,000 or more) and if done badly can compromise the car's safety. On an older car worth a few thousand pounds, structural corrosion often makes the car uneconomical to repair.
Steering Rack Play
Excessive play in the steering rack is expensive to fix (£400 to £1,000 for a replacement) and indicates the car has been driven with worn components for a long time, which suggests broader maintenance neglect.
Major Brake Defects
While worn pads and discs are normal, a failure for a corroded or seized brake caliper, a fractured brake line, or a faulty ABS module is more serious. Caliper replacements cost £150 to £400 each. Brake line replacement costs £100 to £300 per line. An ABS module can cost £500 to £1,500.
You can check the exact safety score for any model on the Euro NCAP website.
Crash Damage Evidence
If the MOT notes mention misaligned bodywork, evidence of previous structural repair, or panel gaps that suggest crash damage, this raises serious questions about the car's history that go beyond the MOT failure itself.
How To Use MOT Failures in Negotiation
If you find a car with an MOT failure that falls into the cheap or moderate fix category, use it as a negotiation tool.
First, get a quote for the repair work from a local garage. This gives you a concrete number to present to the seller. Then approach the negotiation like this:
"The car has failed its MOT for worn brake discs and suspension bushes. I have had a quote of £450 to put it right. I would like to offer the asking price minus the repair cost."
The FCA has a useful guide to car finance that explains your rights and what to watch for.
This is a reasonable and factual approach. Most sellers will accept a reduction that reflects the genuine cost of the required work, especially if the car has been sitting unsold because of the failed MOT.
Step-by-Step Process for Buying a Car With a Failed MOT
- Check the MOT history online and identify exactly what caused the failure
- Research the typical cost of fixing each failure item
- Add up the total repair cost and decide if the car is worth pursuing at the asking price minus that cost
- Run a full vehicle history check to ensure there are no hidden issues beyond the MOT failure
- View the car and inspect it thoroughly, paying particular attention to the failed items
- Get a written repair quote from an independent garage
- Make your offer based on the asking price minus the repair costs
- If the seller agrees, get the repairs done, book the MOT retest, and confirm it passes before completing the sale
Dave's Verdict
A failed MOT is not automatically a reason to walk away. Some of the best Used Car deals come from cars with minor MOT failures that have frightened off less informed buyers. The key is understanding what caused the failure, how much it will cost to fix, and whether the car represents good value once those costs are factored in.
But always combine your MOT analysis with a full vehicle history check. A failed MOT tells you about the car's current condition. A history check tells you about its past, including finance, write-offs, stolen markers, and mileage verification. Together, they give you the complete picture.
Use Dave to check any car you are considering. Even if the MOT looks fine, the history check might reveal something that changes everything.
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