You've bought a car and something's wrong. But is it a "fault" in the legal sense? Can you actually reject it? Here's how to tell.
The Legal Test
Under the Consumer Rights Act 2015, you can reject a car if it fails one of three tests:
- Not of satisfactory quality – It has defects a reasonable person wouldn't expect
- Not fit for purpose – It can't be used as a car should be used
- Not as described – It doesn't match what you were told
A "fault" is anything that causes the car to fail one of these tests.
Clear-Cut Faults
These are almost always grounds for rejection:
Mechanical Failures
- Engine won't start or runs poorly
- Gearbox grinding, slipping, or failing
- Clutch juddering or not engaging
- Brakes not working properly
- Steering issues (heavy, pulling, noise)
- Suspension failures
- Cooling system leaks or overheating
Electrical Problems
- Battery not holding charge (beyond normal age)
- Central locking failures
- Windows not working
- Dashboard warning lights that won't clear
- Infotainment system failures
- Sensor malfunctions
Safety Issues
- Airbag warning lights
- ABS/traction control failures
- Seatbelt problems
- Structural issues
- Brake failures
Undisclosed Issues
- Accident damage not revealed
- Outstanding finance
- Clocked mileage
- Previous write-off status
- Hidden rust or corrosion
Grey Area "Faults"
These depend on context:
Wear Items
Brakes, tyres, and clutches wear out. Whether wear constitutes a fault depends on:
- Were they disclosed as worn?
- Is the wear appropriate for mileage?
- Did they fail prematurely?
A clutch that fails at 20,000 miles is likely faulty. One that's worn at 80,000 miles is probably just wear.
Cosmetic Issues
Scratches, dents, and interior wear are usually acceptable on used cars IF:
- They match the car's age and price
- They were visible at viewing
- They weren't concealed
A scratch on a £3,000 car is different from one on a £30,000 car.
Age-Related Issues
Older cars have more problems. But age doesn't excuse:
- Fundamental mechanical failures
- Safety issues
- Problems that weren't disclosed
- Rapid deterioration after sale
Intermittent Problems
Faults that come and go can be tricky:
- They're still faults if they affect the car's quality
- Document when they occur
- Video evidence is powerful
- Diagnostic codes often capture intermittent issues
What's NOT Usually a Fault
Normal Characteristics
- Diesel clatter
- Turbo whistle
- Firm sports suspension
- Features that work as designed (even if you don't like them)
User Preference
- Fuel consumption matching manufacturer figures
- Road noise typical for the model
- Handling characteristics normal for the car
- Features you didn't check before buying
Post-Sale Damage
- Issues caused by your driving
- Accident damage after purchase
- Problems from neglected maintenance
- Modifications that caused issues
Disclosed Issues
- Problems the dealer told you about
- Faults reflected in a lower price
- Issues you agreed to accept
The Timing Question
When did the fault exist?
Within 30 Days
Any fault present at delivery = right to reject. Learn more about the 30-day rejection timeline. You don't need to prove when it developed. If it's there within 30 days, it's presumed to have been there at sale.
Within 6 Months
Faults are presumed to have existed at sale unless the dealer can prove otherwise. The burden of proof is on them.
After 6 Months
You need to prove the fault existed at sale. Usually requires an independent inspection showing the problem pre-dated your purchase.
How to Prove a Fault
Documentation
- Photos and videos of the problem
- Dashboard warning light images
- Mileage at each occurrence
- Dates and times
Diagnostic Evidence
- OBD fault codes
- Dealer diagnostic reports
- Independent garage assessments
- Error logs from the car's computer
Expert Evidence
- Independent inspection reports
- Mechanic's written opinion
- Technical assessments
- Manufacturer technical bulletins
Pattern Evidence
- Online forums showing common issues
- Recall notices
- Technical service bulletins
- Similar complaints to Trading Standards
Real Examples
✅ IS a Fault
Problem: Engine management light comes on after 2 weeks, diagnostic shows injector fault. Why: Mechanical failure affecting performance, present within 30 days.
✅ IS a Fault
Problem: Car described as "full service history" but missing 3 years of stamps. Why: Not as described – the description was false.
✅ IS a Fault
Problem: 4-year-old BMW gearbox fails at 45,000 miles. Why: Premature failure – gearboxes should last much longer.
❌ NOT a Fault
Problem: Brakes need replacing at 60,000 miles. Why: Normal wear item at typical interval.
❌ NOT a Fault
Problem: Diesel engine is noisy. Why: Characteristic of diesel engines, not a defect.
⚠️ DEPENDS
Problem: Air conditioning doesn't blow cold. Why: Fault if not disclosed; acceptable if sold as "AC needs regas" at reduced price.
What If the Dealer Disagrees?
Dealers often claim:
- "That's not a fault, it's wear and tear"
- "All cars of this age have that"
- "You should have spotted it"
Your responses:
- "The law defines satisfactory quality, not you"
- "Age doesn't remove the requirement for basic functionality"
- "Your duty is to sell satisfactory goods, not mine to be an expert"
If they won't accept it's a fault:
- Get an independent inspection
- Put your rejection in writing
- Contact your finance company (if applicable – they're jointly liable)
- Escalate to court if necessary
The Bottom Line
A "fault" is anything that makes the car not of satisfactory quality, not fit for purpose, or not as described.
The key questions are:
- Would a reasonable buyer expect this problem?
- Does it affect the car's functionality or safety?
- Was it disclosed before purchase?
- Is it appropriate for the car's age, mileage, and price?
If the answers suggest you've been sold a substandard product, you likely have grounds to reject.
Not sure if your problem counts as a fault? Get a free assessment – we'll tell you where you stand.
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