# Deletes: what you need to know first

> Deleting the DPF, EGR or AdBlue is not allowed on vehicles driven on public roads. What the law says, what the alternatives are and when it is done.

- URL: https://www.reprogramacionesmbv.com/en/deletes/
- Index for AI (llms.txt): https://www.reprogramacionesmbv.com/en/llms.txt
- Versión en español: https://www.reprogramacionesmbv.com/anulaciones/
- Reviewed: 2026-10-15

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If you have landed here, you probably have a particulate filter, an EGR valve or an AdBlue system playing up. Before talking about deleting anything, we go through the regulations to show what it means for a car driven on the road and what other ways out the fault has.

**In short:** A delete disables an emissions control system in software, and sometimes by removing the part: the DPF (diesel particulate filter), the EGR valve or AdBlue (SCR). In Spain it is not allowed on vehicles driven on public roads: Royal Decree 920/2017 classes a missing, modified or non-working emissions control system as a major defect, so the car fails its ITV (Spain's compulsory vehicle inspection); driving without meeting the technical requirements is a serious offence under the Traffic Act, and your insurer can reduce or refuse a payout. That is why we only do deletes on competition vehicles or vehicles not used on public roads. If yours is a road car, we diagnose the fault and fix it.

**Not allowed on vehicles driven on public roads**

Deleting the particulate filter, the EGR, AdBlue, the catalytic converter or any other emissions control system **is not allowed on a vehicle driven on public roads in Spain**. What the regulations say:

- **ITV.** Real Decreto 920/2017 (Spain's vehicle inspection regulation), Annex I, sections 8.2.1.1 and 8.2.2.1, classes as a **major defect** any emissions control equipment fitted by the manufacturer that is missing, modified or clearly malfunctioning. The ITV is Spain's compulsory periodic vehicle inspection, similar to the UK MOT. A major defect means a **fail**: the vehicle may only be driven to the workshop and back to the inspection.
- **Driving and fines.** The Traffic Act prohibits driving a vehicle whose emissions exceed the limits or that has a vehicle modification (reforma) that must be legalised but has not been authorised (art. 12.7 of Real Decreto Legislativo 6/2015, Spain's Traffic Act). Driving a vehicle that does not meet the technical requirements is a **serious offence** (art. 76.o), punishable by a fine of 200 euros (art. 80.1).
- **Insurance.** The Ley de Contrato de Seguro (Spain's Insurance Contract Act), arts. 10 to 12, requires you to report anything that increases the risk. If you do not and there is a claim, the insurer can reduce the payout or, where there has been bad faith, not pay at all.

That is why **we only do deletes on competition vehicles or vehicles not used on public roads**, and we will ask how the vehicle is used before accepting the job. You will find all the regulations explained in [legality, ITV and insurance](https://www.reprogramacionesmbv.com/en/legality-itv-insurance/).

## What a delete is and how it differs from a remap

A **remap** such as [Stage 1](https://www.reprogramacionesmbv.com/en/ecu-remapping/stage-1/) changes how the engine works (turbo, injection, torque) but leaves every emissions control system working. A **delete** does the opposite: it is not after more power, it makes the ECU stop using or monitoring a particular system. It usually has two parts:

1. **Software**: the ECU stops managing the system and stops logging faults related to it.
2. **Physical**, in some cases: the part is removed or emptied (the filter, the catalytic converter) or a passage is blanked off (the EGR).

The first can be undone if the original was saved. The second cannot, short of fitting new parts. Many people come to us asking for a delete when what they really have is a fault that can be repaired, and that difference is what saves the most money.

## The systems usually deleted and why they fail

| System | What it does | Why it tends to play up | What to check first |
|---|---|---|---|
| [AdBlue / SCR](https://www.reprogramacionesmbv.com/en/deletes/adblue/) | Injects urea into the exhaust to reduce nitrogen oxides | Crystallisation, tank pump or heater, NOx sensor | Fluid quality, sensors and pump |
| [DPF](https://www.reprogramacionesmbv.com/en/deletes/dpf/) | Traps soot from the exhaust and burns it off in regenerations | Short trips that do not allow it to regenerate, differential pressure sensor | Accumulated ash, sensor, regeneration history |
| [EGR](https://www.reprogramacionesmbv.com/en/deletes/egr/) | Sends part of the exhaust gas back into the intake | Carbon build-up that blocks it or leaves it open | Cleaning, actuator and air mass meter |
| GPF / OPF | Particulate filter on petrol engines | The same as the DPF, on petrol | Same as the DPF |
| Lambda sensor / catalytic converter (O2) | Measures oxygen in the exhaust and monitors the catalytic converter | Ageing sensor, degraded catalytic converter | Sensor readings before and after the catalytic converter |
| SAP (secondary air) | Injects air into the exhaust when cold so the catalytic converter warms up sooner | Seized pump or valve | Pump, valve and pipes |
| EVAP | Collects vapours from the fuel tank | Leaks, purge valve | Leak test |
| Swirl flaps / TVA | Intake flaps and throttle | Spindle wear, carbon build-up | Actuators and play |
| MAF (air mass meter) | Measures the air entering the engine | Dirt or ageing of the sensor | Live values versus expected values |

There are other functions people also ask to have "deleted" that **are not emissions control systems**, although they have their own nuances:

- **Start&Stop**: most cars let you switch it off with a button every time you start. Disabling it permanently means changing the factory configuration.
- **Immobiliser (Immo)**: it is an anti-theft protection. Disabling it makes sense in motorsport or with an unprogrammed replacement ECU, but on a road car it leaves the vehicle more exposed and your insurer may require it. The right solution is almost always to [clone the ECU](https://www.reprogramacionesmbv.com/en/ecu-cloning/) or sort out the [no-start problem](https://www.reprogramacionesmbv.com/en/no-start-solutions/).
- **DTC (fault codes)**: hiding a code does not fix the cause. It only makes sense when the component no longer exists on a competition vehicle.

## Before deleting: the fault can almost always be fixed

We are a workshop (Ronda de la Pescadería, 24, bajo, 28801 Alcalá de Henares (Madrid)), so the first thing we suggest is finding out why the system is failing. [Electronic diagnostics](https://www.reprogramacionesmbv.com/en/vehicle-diagnostics/) show whether the problem is the component, a sensor giving a false reading, the wiring, or a usage pattern that does not let the system do its job (for example, a DPF on a car that only does short trips). With that we give you a quote for the repair, and you decide with all the facts.

If your car has already been deleted somewhere else and you want to pass the ITV with peace of mind, what you need is the opposite: get the [original software](https://www.reprogramacionesmbv.com/en/back-to-stock-software/) back and, if it is missing, refit the component.

## When a delete does make sense

- **Competition vehicles** used on circuits or at events that are not driven on public roads.
- **Vehicles and machines that only work inside closed premises or private land**, without going onto public roads.

In those cases we work just as we do on a remap: a saved copy of the original software, a modification developed for that specific ECU and a check afterwards. The most requested ones have their own page: [AdBlue](https://www.reprogramacionesmbv.com/en/deletes/adblue/), [DPF](https://www.reprogramacionesmbv.com/en/deletes/dpf/) and [EGR](https://www.reprogramacionesmbv.com/en/deletes/egr/).

- [AdBlue](https://www.reprogramacionesmbv.com/en/deletes/adblue/): Start countdown, NOx sensor, pump or crystallisation: what fails and how it is fixed.
- [DPF](https://www.reprogramacionesmbv.com/en/deletes/dpf/): Why the diesel particulate filter clogs, how it regenerates and what to do before you even think about deleting it.
- [EGR](https://www.reprogramacionesmbv.com/en/deletes/egr/): Jerking, smoke or limp mode: how to tell whether it is the EGR and how it gets fixed.

## What we need to assess it

- Make, model, engine and year of the vehicle.
- What the symptom is: warning light on, limp mode, AdBlue message, constant regenerations…
- Whether anything has been done to it before (cleaning, parts replaced, modified software).
- What the vehicle is used for: road, motorsport or closed premises.

Tell us the symptom and the vehicle. We will tell you what might be going on and what options you have, starting with the ones that let you pass the ITV.

## Frequently asked questions

### Do you do deletes on cars driven on the road?

No. On a vehicle driven on public roads, a missing or modified emissions control system is a major defect at the ITV and driving like that is an offence. What we do is diagnose why the DPF, EGR or AdBlue is failing and give you a quote to fix it.

### Can the ITV tell that a system has been deleted?

Royal Decree 920/2017 includes reading the on-board diagnostic system (OBD) among its emissions inspection methods, alongside a visual inspection of the emissions control equipment and gas or opacity measurement. A badly done delete leaves fault codes; a well done one tries not to leave any, but that does not make it legal: the defect is that the system is missing or modified, whether it is detected or not.

### I bought a car that had already been deleted. What should I do?

First you need to know what was done: whether only the software was changed or the part was also removed. If the component is still fitted, writing back the ECU's original software is often enough; we explain it under [back to stock software](https://www.reprogramacionesmbv.com/en/back-to-stock-software/). If it was removed, it will need refitting. We assess it for you with a [diagnosis](https://www.reprogramacionesmbv.com/en/vehicle-diagnostics/).

### Can a delete be reversed?

The software side can, as long as the ECU's original file was saved, which is the first thing we do on any job. The physical side cannot: if the filter or the catalytic converter has been emptied or removed, a new one has to be fitted.

### What happens with my insurance if the car has something deleted?

Spain's Insurance Contract Act requires you to declare to the insurer any circumstances that increase the risk. If you do not and there is a claim, the insurer can reduce the payout proportionally or, in cases of bad faith, be released from paying. Also check your policy's terms on vehicle modifications.

### And if it is for motorsport, what do you need?

Tell us what the vehicle is used for and how it gets to the circuit or the venue. We discuss it before accepting the job and, as with any remap, we copy the original software first.

## Sources

- [Royal Decree 920/2017 regulating vehicle inspection (ITV), Annex I, sections 8.2.1.1 and 8.2.2.1 (BOE, Spain's official gazette)](https://www.boe.es/buscar/act.php?id=BOE-A-2017-12841)
- [Royal Legislative Decree 6/2015, Spain's Traffic, Motor Vehicle and Road Safety Act, arts. 12.7, 76.o) and 80.1 (BOE, Spain's official gazette)](https://www.boe.es/buscar/act.php?id=BOE-A-2015-11722)
- [Act 50/1980 on Insurance Contracts, arts. 10 to 12 (BOE, Spain's official gazette)](https://www.boe.es/buscar/act.php?id=BOE-A-1980-22501)
- [Royal Decree 866/2010 on vehicle modifications (BOE, Spain's official gazette)](https://www.boe.es/buscar/act.php?id=BOE-A-2010-11154)