Why you have to declare it

A remap changes your car's power output, which is exactly the kind of change an insurer needs to know about to price your policy accurately. Under the terms of virtually every UK car insurance policy, performance modifications must be declared — not declaring one is treated as non-disclosure, and non-disclosure is one of the most common reasons a genuine claim gets refused.

This matters even if the remap had nothing to do with whatever you're claiming for. An insurer who discovers an undeclared modification after an accident can refuse the claim, or void the policy entirely, purely on the grounds that the information they were given when the policy was set up wasn't accurate.

Non-disclosure isn't a technicality: insurers regularly reject claims specifically because of an undeclared modification found during investigation, regardless of how the incident itself happened. Declaring it up front is the only way to be properly covered.

What actually happens to your premium

It depends on the type of remap and the insurer. A performance-focused remap that increases power output is the modification most likely to raise your premium, since it's assessed as increasing risk. An economy-focused remap, aimed at fuel efficiency rather than outright power, is sometimes treated more favourably and can have little effect on the premium, or occasionally reduce it slightly.

  • Performance remaps are the most likely to increase premiums, in line with the power increase
  • Economy-focused remaps are sometimes assessed more favourably
  • Specialist or performance-car insurers are often more comfortable pricing a remap accurately than a mainstream insurer
  • The exact effect varies significantly between insurers — it's always worth getting a quote before committing

How to declare it properly

Contact your insurer directly (or your broker, if you use one) and tell them the vehicle has had an ECU remap, including whether it's a performance or economy-focused tune. Most insurers will ask for the approximate power increase, which we can confirm from the before-and-after figures on your dyno printout — every remap we carry out is verified and measured, so you have genuine figures to give them rather than a guess.