Learn how to spot red flags, understand defect types, and avoid buying problem cars. Expert guide covering dangerous defects, mileage clocking, and critical warning signs in MOT history reports.
Every year, thousands of UK car buyers unknowingly purchase vehicles with hidden problems. The MOT history is your first line of defense against clocked mileage, dangerous defects, and costly repairs waiting to happen. This comprehensive guide will teach you how to read MOT reports like a professional, spot the red flags that dealers hope you'll miss, and make confident, informed buying decisions.
Whether you're a first-time buyer or an experienced car enthusiast, understanding what MOT reports reveal - and what they hide - is crucial. Our interactive examples below demonstrate real-world scenarios you'll encounter when researching used vehicles.
Since May 2018, the UK DVSA introduced a clearer defect classification system. Every fault found during an MOT test is categorized as Dangerous, Major, Minor, or Advisory. Understanding these categories is essential for evaluating a vehicle's true condition.
| Defect Type | MOT Result | Can You Drive? | What It Means |
|---|---|---|---|
Dangerous | FAIL | NO - Illegal to drive | Immediate safety risk. Invalidates existing MOT. Must be repaired before driving. |
Major | FAIL | Only to repair appointment if roadworthy & MOT still valid | Affects safety or environment. Must be fixed and retested before certificate issued. |
Minor | PASS | YES | No significant safety impact. Repair soon but MOT certificate still issued. |
Advisory | PASS | YES | Component will deteriorate soon. Monitor and address before next MOT. |
Dangerous defects pose an immediate risk to your safety and that of other road users. Common examples include:
If you're buying: Walk away. Any car with recent dangerous defects, even if subsequently repaired, should be thoroughly inspected by a trusted mechanic before purchase.
Example: View our "All Defect Types" scenario below to see dangerous defects in action.
Major defects are serious enough to cause MOT failure but don't pose the immediate danger of a dangerous defect. However, they indicate significant safety or environmental concerns that must be addressed before a certificate can be issued.
Key point: You can legally drive a vehicle with major defects ONLY if:
Common major defects include:
Buyer's Tip: A recent major defect followed immediately by a pass suggests the issue was fixed. However, recurring major defects in the same area (e.g., suspension problems year after year) indicate an underlying issue that will continue to cost money.
Example: Check our "Recent Failure" and "Mixed History" scenarios to see major defects and their patterns.
Minor defects won't cause an MOT failure, but they shouldn't be ignored. These indicate components that are technically defective but not yet serious enough to pose safety risks or environmental concerns.
Examples of minor defects:
For buyers: Minor defects are useful negotiation points. While not dangerous, they represent work the seller should have addressed. Calculate repair costs and use this to negotiate the price down.
Advisories are perhaps the most valuable information in an MOT report for used car buyers. They indicate components that aren't yet defective but are showing signs of wear and will likely need attention soon.
Common advisories include:
Example: Our "Pass with Advisories" scenario demonstrates multiple advisory items and what they mean for a potential buyer.
A "perfect" MOT history - all passes, no defects, consistent mileage progression - looks attractive but isn't the whole story. Even well-maintained cars develop advisories over time.
What to verify:
Example: View our "Perfect Record" scenario - then consider what additional checks you'd want to perform.
Clocking refers to illegally tampering with a vehicle's odometer to show lower mileage than the car has actually covered. This makes the car appear more valuable and hides the wear and tear from high-mileage use.
How to spot clocked mileage:
Mileage dropped by 34,870 miles - clear sign of clocking. Walk away from this vehicle.
What clocked mileage means for you:
Example: Our "Mileage Discrepancy" scenario shows exactly what clocking looks like in an MOT history. This is essential viewing for any used car buyer.
MOT failures aren't automatically a reason to avoid a vehicle. In fact, most cars fail an MOT at some point in their lifetime. What matters is the context: what failed, when it was fixed, and whether the same issues keep recurring.
Evaluate MOT failures by asking:
Good Sign: Failed MOT on 15 Jan 2024, passed retest same day with "front nearside brake disc worn" fixed. Shows responsible ownership and immediate action.
Bad Sign: Failed MOT 15 Jan 2024, no retest shown, seller claims "it's all fixed now." Without proof of retest, you're trusting their word that dangerous defects were properly repaired.
Example: Compare our "Recent Failure" and "Mixed History" scenarios to see the difference between acceptable and concerning failure patterns.
Experienced buyers know that an MOT history often reveals what sellers try to hide. Here are the warning signs that should make you think twice - or walk away entirely.
Action: Walk away immediately. Report to Trading Standards if you have proof.
Action: Budget for these repairs to recur. Factor into negotiation or walk away.
Manufacturers issue recalls for safety-critical defects. An outstanding recall means the vehicle has a known safety issue that hasn't been fixed.
Action: Insist recall is fixed before purchase or factor delay into price negotiation.
Example: Our "Outstanding Recall" scenario shows how this appears in MOT reports.
Missing MOT tests suggest periods when the vehicle was off the road. This could be legitimate (SORN - Statutory Off Road Notification) or concerning (unroadworthy, hidden damage).
Action: Request full service history to explain gaps. If unavailable, assume worst case.
Most cars consistently show "DVSA" as the data source. Variations can indicate vehicle history changes.
Action: Verify with V5C logbook. Commercial history may mean higher wear.
Below you'll find 10 different MOT report scenarios demonstrating common situations you'll encounter when researching used vehicles. Each example uses realistic dummy data to show you exactly what to look for.
Establish a baseline understanding of what an ideal MOT history looks like.
See every severity level in one report - Dangerous, Major, Minor, and Advisory.
Critical for buyers - learn to spot clocking that could cost you thousands.
Understand the difference between acceptable and concerning defects.
Most real-world vehicles have complex histories - learn to interpret patterns.
Use our free MOT checker to view complete history for any UK vehicle. Official DVSA data, no registration required.
Check MOT History Now →Ready to see these concepts in action? View our interactive MOT report examples to practice identifying defects, spotting clocking, and reading real-world patterns.