What to tell your insurer
Describe the proposed change as an ECU remap. Say whether it’s a performance or economy tune, and mention a gearbox tune or hardware change if you’re planning one. Give the insurer the vehicle details and ask what information it needs from the installer. If it asks for power figures, check which figures A* can substantiate for your exact engine and calibration.
Try saying, “I’m considering a Stage 1 ECU remap on my car. Can you confirm whether you’d continue to cover it, what it would cost, and when I need to tell you the work has been done?” Ask for the answer in writing and keep it with your policy details.
If you’ve bought a used car and discover it was previously tuned, contact your insurer once you know. See the Financial Ombudsman’s guidance on car modifications.
What the MOT checks
For cars and passenger vehicles, the relevant DVSA checks depend on the vehicle and fuel type. The test can include exhaust emissions, visible emissions-control equipment and the engine warning lamp where applicable. Missing, obviously modified or defective emissions-control equipment can be a major defect under the applicable criteria. The diesel checks also cover signs that the diesel particulate filter has been tampered with.
A car still needs to meet the applicable standards after a software change. If a warning light is on, smoke has increased or an emissions fault is present, arrange diagnosis first. The DVSA MOT inspection manual sets out the test criteria.
Warranty, finance and paperwork
If the car has a warranty, check how the provider treats ECU tuning and related claims. For a leased or financed car, read your agreement and ask the provider about permission where required. The A* calibration warranty covers qualifying faults attributable to our calibration under its terms.
Keep the invoice, the details of the work and any written response from your insurer. If you later reinstate a tune after a dealer update or return the car to stock, ask your insurer how it wants the change recorded.