Legality, ITV and insurance

Summary in one table

Is it legal to remap a car in Spain?

Yes, provided it is legalised as a modification where required. There is no general ban on modifying an engine's software, but a registered vehicle has approved characteristics (those shown on its ITV card, the tarjeta ITV), and changing them after registration is a modification (reforma).

Real Decreto 866/2010 (Spain's regulation on vehicle modifications) governs the procedure for modifying vehicles that are already registered, and refers to the Manual de Reformas de Vehículos (the Vehicle Modifications Manual), published by the Ministry of Industry. The current revision (seventh revision, second correction) was approved by a resolution published in the BOE on 5 February 2026. In that manual, remapping has its own code:

The key lies in the phrase "that may change the maximum power". A remap aimed at gaining power falls squarely within it. For adjustments that don't seek to change the maximum power (for example, some aimed only at fuel consumption or throttle response) the answer is less obvious and depends on what is modified and on the technical service's judgement: if that is your case, ask before taking anything for granted.

How an ECU remap is legalised

1. Conformity report

   issued by a technical service designated for vehicle modifications or by the vehicle manufacturer (Art. 5.3 of RD 866/2010). It shows that the modified vehicle still complies with the applicable regulations: emissions, noise and engine power, among others.

2. Workshop certificate

   the workshop that made the modification certifies the work carried out, using the template in the Vehicle Modifications Manual. If the remap is ours, we issue it.

3. Application

   submitted by the vehicle's registered keeper or a person authorised by them (Art. 7.1).

4. ITV inspection

   within a maximum of fifteen days of the modification (Art. 8.1), with the documentation. The station checks the work and, if the result is a pass, records the modification and the new power on the ITV card.

Some details of code 2.9 worth knowing: the emissions standard in force on the vehicle's date of registration is accepted; if the modification changes the top speed, the tyre speed rating has to be up to it; and if the remap goes together with other modifications (turbo, intake, exhaust), each one is processed with its own requirements.

We issue the workshop certificate

If we remap your vehicle and you want to legalise the power increase, we issue the workshop certificate for code 2.9, as the workshop that made the modification. The conformity report still has to come from a technical service or the manufacturer, and the inspection from the ITV station.

The periodic ITV and an ECU remap

At the periodic inspection, the ITV (Spain's compulsory periodic vehicle inspection, similar to the UK MOT) checks that the vehicle matches its documentation and examines, among other things, its emissions. Real Decreto 920/2017 (Spain's regulation on vehicle roadworthiness inspection) sets out how: a visual inspection of the emissions control equipment and measurement of gases (petrol) or opacity (diesel), or reading the on-board diagnostic system (OBD), depending on the case.

Two ideas worth keeping apart:

• The ITV not detecting it doesn't make it legal. The obligation to legalise the modification exists whether or not the station detects it.
• An adjustment that keeps the emissions control systems still performs in the emissions test like a standard one. That doesn't exempt it from the modification procedure if the power changes, but it does make the difference compared with a delete.

Deletes and the ITV

Here the regulation is clear. Annex I of Real Decreto 920/2017 classes the following as a major defect:

• On petrol engines (section 8.2.1.1): emissions control equipment fitted by the manufacturer that is missing, modified or obviously defective.
• On diesel engines (section 8.2.2.1): emissions control equipment fitted by the manufacturer that is missing or obviously defective.

A major defect means a failed inspection and, under Article 11.2, the vehicle may not be driven except to go to the workshop and back to the station within two months. That is why deletes only make sense on vehicles that are not used on public roads, as we explain under deletes.

What the Traffic Act says

The consolidated text of Spain's Traffic Act (Real Decreto Legislativo 6/2015, the Ley de Tráfico) contains several provisions that may apply to a modified vehicle:

Which of them applies, if any, depends on what has been modified and how the officer or the authorities assess it. The last point is absolute and has no nuances: the speed limiter and tachograph on vehicles required to have them are not touched, at our workshop included.

Insurance

Law 50/1980 on Insurance Contracts (Ley de Contrato de Seguro) sets out two duties of the policyholder that directly affect an ECU remap:

• When taking out the policy (Art. 10): declaring the circumstances you know of that may influence the assessment of the risk, according to the insurer's questionnaire.
• During the contract (Art. 11): notifying, as soon as you can, any changes that increase the risk and which, had they been known, would have led the insurer not to provide cover or to do so on more expensive terms.

If it isn't notified and there is a claim (Art. 12), the insurer is released from paying if there was bad faith and, if there wasn't, it reduces the payout in proportion to the difference between the premium it charged and the one it would have charged. Whether a remap increases the risk or not is for each insurer to assess: the safe way to find out is to ask them in writing.

And damage to third parties? The compulsory insurance still pays them: the insurer cannot rely against injured parties on clauses excluding, for example, vehicles that fail to meet technical requirements (Art. 6 of RDL 8/2004). But once it has paid, it can recover the money from the policyholder or the insured on the grounds set out in the Insurance Contract Act (Art. 10(c) of the same text). In other words: the injured party gets paid, and the bill may end up landing on you.

The manufacturer's warranty

There are more nuances here than clear-cut rules, so we tread carefully:

• The legal guarantee requires the seller to answer for any lack of conformity that existed at the time of delivery and becomes apparent within three years (Art. 120 of the consolidated consumer protection act). A fault caused by a later modification is not an original lack of conformity.
• The manufacturer's commercial warranty, the one that goes beyond the legal guarantee, is governed by the terms of its own warranty statement (Art. 127), and many exclude damage arising from unauthorised modifications.
• In practice, the argument will be about whether the fault is related to the modified software. If the manufacturer maintains that it is, it may refuse the repair, and proving otherwise isn't always easy. When it connects its equipment or updates the ECU, the dealer may see that the software isn't the factory one.

Our advice for a car under warranty is simple: if it worries you, wait until it runs out. If it is already remapped and you are going to the dealer, the clean option is to go back to the original software beforehand, which we always keep.

What we do with all this

• Before we start, we explain what the job means in your case, as on every service page (Stage 1, for example).
• Before remapping, we always copy the original software, which is what makes it possible to go back to stock. We cover this under how we work.
• We don't carry out deletes on vehicles used on public roads, and we don't touch speed limiters, tachographs or odometers.

If you have a specific question, we also cover it, in shorter form, in the FAQs.

Reviewed on 15 October 2026.