One in 12 UK Sellers Would Hide a Costly Fault (and How to Spot One)

• A survey of 2,000 UK car owners found one in 12 would sell a car with a costly fault without telling the buyer, and 3% would say nothing even if asked directly.
• Private car sales carry far less legal protection than buying from a dealer, so most of the burden of checking a car’s history falls on the buyer.
• Free tools like the DVSA’s MOT history checker, and a direct question asked in writing, can catch problems a test drive alone won’t reveal.

Buying Privately Means Buying on Trust Alone

Buying a used car from a private seller means buying mostly on trust. There’s no returns desk, no manager to escalate to, and in most cases, far less legal protection than walking into a dealership. New research puts a number on how often that trust gets broken.

What the Research Found

A survey of 2,000 UK car owners, carried out by OnePoll on behalf of the diagnostics firm Carly, found that around one in 12 would sell a car with an expensive fault without volunteering that information to the buyer. Five per cent said they would only admit to the fault if asked directly, while three per cent said they would say nothing at all, even then.

The figures get worse at certain ages. More than one in seven car owners between 35 and 44 said they would either stay quiet or wait to be asked, more than four times the rate among owners aged 65 and over, who were the most likely to disclose a fault unprompted. Geography played a role too: sellers in Wales and London were the most likely to hold back, at 13% and 12% respectively, while sellers in the South West were the most upfront, with just 5% prepared to stay silent.

There’s a more reassuring side to the numbers. Almost half of car owners, 49%, said they would do the decent thing: a quarter would come clean and reduce the price to reflect the fault, and 24% said they would pay to fix the problem before selling. Most sellers aren’t trying to catch anyone out. But a real question remains: how does a buyer tell an honest seller from one of the minority who isn’t?

Why Private Sales Carry So Little Protection

The protection buyers get from a dealer doesn’t carry over to a private sale. Buying from a trader, a car has to match its description and be of satisfactory quality and fit for purpose, with a right to a repair, replacement or refund if it doesn’t. Buy from a private individual and none of that applies. The seller only has to own the car and describe it truthfully; beyond that, the old principle of caveat emptor, buyer beware, still does most of the work.

That doesn’t mean a lying seller is completely in the clear. If a seller gives a false answer to a direct question, rather than simply staying silent, that can amount to misrepresentation, and a buyer who can prove it was given in writing has a stronger case than one relying on a verbal exchange at the roadside. It’s a reason to ask questions plainly and keep a record of the answer, rather than take a seller’s word on trust and hope for the best.

Free Checks Before You Hand Over Money

Several checks cost nothing and take minutes. The MOT history of any car registered in the UK can be checked free on GOV.UK, showing every pass, fail and advisory going back years. A string of repeated advisories that were never fixed, or a mileage reading that doesn’t climb steadily year on year, is worth asking about directly before agreeing a price.

A logbook, service history and the car’s V5C registration document are worth checking too; a seller who can’t produce them, or whose name doesn’t match the V5C, is a reason to walk away rather than push ahead. None of these checks catch everything. Plenty of faults, especially inside a car’s electronics, don’t show up on a test drive or in the paperwork, and some only reveal themselves once the car has been driven for a few hundred miles.

What to Ask Before You Pay

Asking a direct question is the single most useful thing a buyer can do: it turns a seller’s silence into an answer on record. “Are there any faults, warning lights or recent repairs I should know about?” is a fair question to put to any seller, and a reasonable one to expect in writing, even a text message, before money changes hands.

Dali Ati, Head of Internationalization at Carly, which markets an OBD port scanner that reads a car’s fault codes before purchase, said: “The vast majority of people selling their car are honest, and almost half would either come clean and knock money off or fix the problem first. But when one in 12 would keep quiet about an expensive fault unless they’re asked, or say nothing at all, buyers shouldn’t have to rely on the seller’s word.

“This isn’t about suggesting every used car has a hidden problem. It’s about bringing more transparency and trust to buying and selling a car, so both sides can shake hands on a deal with confidence.”

A diagnostic scanner plugged into the car’s OBD port, of which Carly’s is one of several on the market, can surface fault codes stored in the car’s systems that wouldn’t otherwise show up before a sale completes. It’s not a free check, and it’s not the only safeguard worth using, but for a buyer about to hand over several thousand pounds on a stranger’s word, it sits alongside the free MOT history check and a straight question asked in writing, rather than replacing either of them.

None of this guarantees a problem-free purchase. But a buyer who checks the MOT history, asks a direct question in writing and looks over the paperwork before agreeing a price is in a far stronger position than one who simply takes a seller’s word for it, and considerably harder for the one in 12 to catch out.