Service history: telling a real one from a fabricated one

A stamped service book is the easiest document in a car to forge. A stamp costs almost nothing and raises the asking price noticeably. So what needs checking is not the book but everything that does or does not agree with it.

Why the book cannot be trusted alone

Stamps go in easily, and the chronology inside them is rarely consistent. The simplest checks on the book itself:

The mileage sequence — it must increase monotonically. An entry with lower mileage after a higher one settles the question immediately.

The intervals in time — realistic gaps, or every entry made with one pen in one evening.

The workshop names — do those businesses exist, can you telephone them.

Handwriting and ink — entries spanning five years are never identical.

What can be verified independently

The main section, because forging any of this takes real effort.

Invoices and job sheets — they list part numbers and oil quantities. Far more specific than a stamp.

A phone call to the workshop named in the book — ask not “was this car serviced” but specifics: when, what was done, at what mileage.

The dealer’s digital record — many manufacturers log servicing centrally, and it can be requested by VIN.

Oil change stickers under the bonnet — they often survive even when the book has been rewritten.

Marker writing on the air filter housing, on a belt, on the battery — mechanics often date their work.

What the car itself shows

Here begins the part that cannot be fabricated.

Consumable condition against claimed mileage. Spark plugs, belt, pads, filters. A fresh filter alongside “just serviced” is consistent; a black one is not.

Manufacture dates on the battery, tyres, and timing belt. Those are marked on the parts themselves and owe nothing to the paperwork; belts are covered in the timing drive article.

Oil condition and level on the dipstick.

Tool marks on the sump plug — fresh marks mean a recent change; no marks at all alongside “regular changes” is a contradiction.

What diagnostics sees

The most valuable part of the check, because counters inside modules are harder to fake than paper.

Freeze frames of old codes — they may carry the mileage at the time of the fault. A mismatch against the odometer settles it; mechanics in the freeze frame article and the odometer fraud article.

Readiness monitors. All reset means codes were cleared recently. Not proof of dishonesty on its own, but a reason to ask; covered in the readiness monitors article.

Diesel regeneration statistics. A high count at low mileage is a contradiction that needs explaining.

Transmission adaptation counters — reset adaptations mean recent intervention.

Engine start counts, where the manufacturer keeps them — the ratio against mileage exposes urban or taxi use; covered in the ex-taxi article.

Red flags

• “We lost the book, but it was always main-dealer serviced.”
• Every entry at one workshop that does not exist or does not answer.
• A perfect book on an imperfect car — where paper and metal disagree, believe the metal.
• Every fluid changed just before sale — that is not care, it is concealment.
• Cleared codes and reset monitors on the day of the viewing.

The checking order

1. Read the book for monotonic mileage and realistic dates.
2. Ask for invoices — they are more specific.
3. Telephone a workshop from an entry.
4. Request the digital record by VIN, if the make supports it.
5. Compare consumables against the claimed service.
6. Read codes, freeze frames, and monitors.

In short

• A stamp costs almost nothing; an invoice with part numbers does not.
• Mileage in the book must rise monotonically; that is the first check.
• Dates on battery, tyres, and belt owe nothing to the paperwork.
• A freeze frame with old mileage beats any stamp.
• Reset monitors on viewing day are a reason to ask, not to hurry.

Download the app — codes, freeze frames, and readiness monitors are read with an ELM327 adapter over Bluetooth SPP on Android.