Buying and selling a used car
What should you check before selling your car?
Read the codes and fix or explain what you find, make sure the readiness monitors are complete, gather the invoices and inspection records and bring the maintenance up to date. A buyer who sees a car with no surprises and with paperwork usually decides sooner and haggles less.
Reviewed by Daniel Morales, founder of Reprorace SL, on
What do I check in the diagnostics?
The trouble codes of every control unit you can read, not just the engine. Decide what to fix and what to explain: a minor warning disclosed up front causes less distrust than one the buyer discovers.
The readiness monitors: if the buyer sees them incomplete, they will think you cleared something. If you repaired and cleared recently, drive for a few days before showing the car.
Which paperwork should I prepare?
The maintenance book or invoices, past inspection records and, if you have it, your country's official vehicle history report, which often includes its inspections.
If the periodic inspection has expired or is about to, getting it done before selling reassures the buyer.
Is a diagnostic report worth it?
A report signed by a shop, with what the control units answered, answers the buyer's questions in advance. Many buyers appreciate it and some ask for it.
Offer it with the invoices. It does not replace any mechanical inspection the buyer wants to have done.
What should I not do?
Clear codes right before showing the car, disconnect the battery to turn off warning lights or touch the odometer. It leaves traces, the buyer can spot it and hiding defects can have legal consequences depending on the country.
Leave accessories plugged into the OBD port without saying so: remove them or explain what they are.
General guidance only: every manufacturer and model has its own details. Always follow your vehicle's manual and, if in doubt, ask a workshop.
Related
Related symptoms
- Engine warning light on and steady: what it means and what to do
- Service reminder or wrench light on the dashboard: what to do
Learn more
See what your car is saying
Before you sell, a shop that works with Diaglana can read your car with the ECO-LITE and issue a signed pre-purchase report, with a QR code so the buyer can check it is genuine.
Presale price: €129 · US$129
Frequently asked questions
Do I have to fix every fault before selling?
In general it is not mandatory, but it is wise to disclose them. What you must not do is hide a defect you know about.
When should I read the codes?
A few days before listing the car, so you have time to repair and for the monitors to complete.
Does a diagnostic report work as a warranty?
No: it describes what the control units answered on the day of the scan. Warranties depend on your country's law and the type of sale.