Remapping and your insurance, warranty and MOT

Why it matters

Insurers set your cover on the car as it is. A remap changes how the engine makes its power, so insurers treat it as a modification, the same as they would new wheels or a body kit.

When you buy or renew a policy, the law expects you to answer the insurer's questions honestly and with reasonable care. Your policy will usually ask you to tell them about changes during the year too, and a remap is one of those changes.

If you don't tell them, they can refuse or reduce a claim, or cancel the policy. That could leave you paying for an accident out of your own pocket.

What it can mean for your cover

It depends on the insurer. Your premium may go up or stay the same, and some insurers don't cover modified cars at all. If yours won't, insurers and brokers that specialise in modified cars can quote instead. Ask before you book the remap, so you know where you stand.

How to tell them

Changing insurer at renewal? Declare the remap again on the new application. A new insurer won't know about it unless you tell them.

What's at stake

A manufacturer's warranty covers faults in how the car was made. A remap changes the engine's software, so the manufacturer or warranty provider may turn down a claim on a part they believe the remap affected, such as the engine, turbo, clutch or gearbox.

How far that goes depends on the terms. Some warranties only exclude the parts a modification could affect, so cover for unrelated parts, such as the bodywork or the infotainment system, carries on. Others are stricter. Read yours, and ask if anything is unclear.

Other warranties

Used-car warranties from a dealer, extended warranties and warranty policies bought separately each have their own terms, and they often say something about modifications. Check every one you have.

Leased or on finance?

If the car is leased, or on PCP or hire purchase, it belongs to the finance company while the agreement runs. Check the agreement before any modification: it may ask you to get the finance company's permission first, and say what condition the car must be in when it goes back.

What the tester checks

The MOT checks that a car meets road safety and environmental standards on the day of the test. On the engine side, that includes:

• an exhaust emissions test, against the limits for the car's age and fuel;
• a check that the emissions equipment the car was built with is still fitted;
• the dashboard warning lights, including the engine warning light.

Emissions equipment must stay fitted and working. If it's missing or has been tampered with, the car can fail its MOT, and using it on the road can be an offence.

Where we stand

We do performance, economy and gearbox tuning only, set up for everyday driving, and we keep your original file. If you have a question about your car and its MOT, ask us before you book.

Before we tune a car, we read its original file and keep a copy on record. Going back to standard means writing that original file back to the car. Even without that file, we can put the factory software back from our own large file database and dealer-level tools.

You might want to go back before you sell the car, before you hand back a leased car, or simply because you'd like the factory settings again.

Selling a remapped car?

If you sell the car with the remap still on, tell the buyer and pass on the paperwork. They'll need to tell their own insurer.

• The invoice or receipt for the work, showing the date, the reg and what was done. Note the mileage on the day as well.
• Your insurer's confirmation: the email or policy schedule that lists the remap.
• Your warranty provider's answer, if you asked them.
• Where your original file is. For work done with us, we keep a copy on record.
• Service history and MOT certificates. You can check your car's MOT history for free on GOV.UK.
• If the car goes back to standard, the date and the paperwork for that too.