Will a remap void my warranty?

A manufacturer warranty is a promise from the manufacturer, on their terms, and every one we have read excludes damage caused by modifications. A remap is a modification. So on a car still under manufacturer warranty, a remap puts the engine, turbo, gearbox and driveline parts of that warranty at risk. It doesn't touch the warranty on the air conditioning, the electrics, the paint or the infotainment, because a remap can't cause those to fail and a dealer can't argue that it did.

What a dealer can and can't refuse

In practice a dealer refusing a claim needs to connect the fault to the modification. A turbo failure on a remapped car is an argument they will usually make and usually win. A failed window regulator isn't. Between the two there's a grey area, a clutch or a DPF for instance, where the outcome depends on the dealer, the manufacturer and how the conversation goes, and you should assume it won't go your way.

Your rights against the retailer who sold you the car, for faults that were there when it was sold, are a separate matter under consumer law and aren't what this page is about. This is about the manufacturer's warranty, and this isn't legal advice.

How a remap is detected

There are three ways. The dealer's diagnostic tool compares the software identifier in the ECU with what the manufacturer expects for that car and flags a mismatch. Some ECUs keep a counter of how many times they have been written to, which a dealer can read. And some manufacturers log a "tuning detected" flag the first time the ECU sees values outside its factory ranges, which stays logged even after the original file goes back on. Which of the three applies depends on the make, the year and the ECU, and we'll tell you plainly for your car.

What we do about it

We keep your original file. It's read and stored the day the remap is done. Before a dealer visit you can ask us to put it back, and the software identifier the dealer reads is then the factory one. This defeats the first method of detection. It doesn't defeat the second or third, where they exist.

We tell you which your car is. If yours is a make that logs a tuning flag, you'll hear it from us before you book, not from a service manager afterwards.

We don't sell you the idea that it's undetectable. Some tuners do. On some cars it's true and on some it's not, and the ones where it's not are the ones where it matters.

So should I wait until the warranty ends?

If the car is under manufacturer warranty and you would struggle to pay for a turbo or a gearbox yourself, yes, and we'll say so. A remap on a car six months out of warranty is worth exactly as much as one on a car six months inside it, and carries none of the risk. If the car is on a lease that ends before the warranty does, put it back to standard before it goes back, which we do free on one visit.

If the warranty has already run out, or the car is old enough that it never had one in your ownership, none of this applies and the only questions left are whether it's safe and what it costs.