Performance remapping is generally legal, but you must declare it to your insurer and the car still has to pass technical inspection. Removing or disabling emissions systems such as DPF, EGR or AdBlue (SCR) is not permitted for road use in the EU, and is supplied for off-road, motorsport and diagnostic use only.
Performance remaps
A Stage 1 or Stage 2 tune that keeps the emissions equipment working is, in most EU countries, legal to fit. The car must still meet roadworthiness, noise and emissions requirements at periodic inspection, and you must declare the modification to your insurer. Some countries also expect the change to be noted at inspection or registration, so check the rules where the vehicle is registered.
Emissions systems: DPF, EGR and AdBlue
Disabling or removing a diesel particulate filter, EGR or the SCR/AdBlue system is treated differently. These systems exist to meet emissions law, and switching them off is not allowed for vehicles used on public roads in the EU. Periodic technical inspection (MOT, TÜV, technische controle and equivalents) increasingly checks for filter presence and emissions output, and penalties can be significant. For that reason these solutions are supplied only for legally permitted off-road, motorsport and diagnostic scenarios.
The rules vary by country
Enforcement and detail differ across the EU. Germany's TÜV, for example, is strict on documented modifications, while other countries handle it differently. It is the vehicle owner's responsibility to comply with local road-traffic and emissions law, wherever the car is driven.
What this means for workshops
Be straight with customers: performance tuning is usually fine when declared, but emissions deletes are not road-legal in the EU. We build these files carefully for permitted use and do not advise fitting them where the law does not allow it.
This article is general information, not legal advice. See the full option list on the services page, or read DPF, EGR and AdBlue explained.
