Yes, you have to tell them. No, it isn't as expensive as the forums claim. What declaring a remap actually involves, what it costs, and why staying silent is the one genuinely dangerous option.
Every week someone asks us, half-joking, 'will insurance ever find out?' It's the wrong question — and this article exists so you never have to ask it. Here's how remapping and insurance actually interact in the UK, with the costs, the process and the one risk that genuinely isn't worth taking.
The rule in one sentence
A remap changes your car's performance from the manufacturer's standard specification, which makes it a modification, and UK insurers require you to declare modifications. Not at renewal. Not if they ask. When it happens. The Association of British Insurers is unambiguous on the principle: material facts must be disclosed, and a performance modification is about as material as facts get.
What happens if you don't
Under the Consumer Insurance (Disclosure and Representations) Act 2012, failing to take reasonable care over disclosure gives your insurer remedies that scale with how deliberate the omission was — from proportionally reduced payouts to voiding the policy entirely and refusing the claim. In practice: a written-off car, no payout, and an insurance record flagged for non-disclosure that follows you to every future quote. Insurers' engineers do inspect ECUs on serious claims. This is the only part of remapping we'd describe as dangerous, and it's entirely self-inflicted.
A remap you haven't declared doesn't save you money. It converts your premium into a donation.
What declaring actually costs
Less than the forums think. The market has matured: millions of UK cars are modified, and mainstream insurers price a Stage 1 remap as routine. Typical outcomes when our customers declare:
- No change at all — common on economy-focused diesel maps and older drivers' policies.
- A modest rise — often in the £20–£80/year range for a Stage 1 on a mainstream car, driver profile depending.
- An admin fee — some insurers charge £15–£30 to amend the policy mid-term.
- A better home — specialist modified-car insurers frequently beat the mainstream quote entirely, because tuned cars are their core book, not an exception.
Young drivers on already-loaded premiums will feel it more — that's honesty, not small print. If the quote comes back silly, shop it: the modified-car specialist market exists precisely for this.
How to declare (five minutes, honestly)
- 01Call your insurer (or use live chat — you'll want a record either way).
- 02Say exactly what was done: 'The engine ECU has been remapped, Stage 1 software only, no hardware changes.'
- 03Give the new figures — your APT invoice states before/after power and torque, which is precisely what they'll ask for.
- 04Get the confirmation in writing on your policy schedule.
- 05Keep your invoice with the paperwork. Done.
Questions we get every week
“It's an economy map, not performance — do I still declare?”
Yes. The ECU no longer matches manufacturer specification; the purpose doesn't change the principle. The good news: economy maps are the cheapest declaration there is, and some insurers don't load them at all.
“The map is undetectable — why bother?”
Because 'undetectable' is a marketing word, not an engineering one. Flash counters, checksum histories and dealer diagnostics have improved every year, and an insurer's engineer investigating a £30k claim is motivated. Declare it, pay the £40, sleep well.
“Will APT tell my insurer?”
No — it's your policy and your responsibility. What we will do is make it easy: documented figures on your invoice, and a straight answer if your insurer's engineer ever wants to talk specifics. It's the same honesty that runs through everything we tune.
About the author
Chris Fisher
Chris writes the APT resource guides. He has spent over 20 years in the motor trade, runs an independent garage in Lancashire alongside Advanced Performance Tuning, and builds the software the trade runs on — including Clarity-GMS, garage management software for UK garages. If something here reads like it was written by someone who has actually had the car on the ramp, that is why.