Locked ECU Unlocking: Bosch MD1 and MG1
Bosch MD1 and MG1 ECUs from 2021 onward are locked from the factory. Unlocking used to mean posting the unit away. It no longer does.
Book a remap →If your vehicle was built from 2021 onward, there is a good chance its engine ECU is one of the protected Bosch MDG1 units. These will accept an official update but will not hand over the software on them, which is why a tuner cannot simply read, map and write one the way they can an older car.
Getting past that is a one-off step called an unlock. Until recently it meant taking the ECU out, posting it to a specialist, waiting, and paying a separate fee. A tooling update has moved that step onto the bench, so it now happens in the same visit as the rest of the work.
We have written up what changed and what it means for you if you want the background on how this used to work.
Posted away, or done here
The unlock itself was never the slow part. Everything around it was: the packing, the postage in both directions, and the days in the middle where nobody had your ECU and the vehicle could not be driven.
Doing it on the bench removes the outside supplier and the two parcels. The unit comes out, gets unlocked, gets read and mapped, and goes back in, all in one appointment.
Which ECUs this covers
Ten Bosch MDG1 designations, across both diesel (MD1) and petrol (MG1) units:
| Family | Designations |
|---|---|
| MD1 (diesel) | MD1CS003, MD1CS004 (HW80), MD1CS005, MD1CS012, MD1CS069, MD1CP006, MD1CP007 |
| MG1 (petrol) | MG1CS002, MG1CS031, MG1CS042 |
If you have arrived here having searched one of those codes, you already know more than most. If you have not, there is no need to: tell us the make, model, engine and year and we will identify the unit.
Every make and model covered
This is the complete list as published by Alientech, covering vehicles built from 2021 onward. It runs well past cars: light commercials and a good deal of agricultural machinery are on it too.
| Make | Models covered |
|---|---|
| Audi | A1, A3, A4, A5, A6, A7, A8, Q2, Q3, Q5, Q7, Q8, TT, S4, S5, S6, S7, SQ5, RS4, RS5 |
| Bentley | Bentayga, Flying Spur |
| Case IH | Farmall 90C, 100C, 110C, 120C, Farmall A Series |
| Citroen | Berlingo, C3, C3 Aircross, C4, C4 Cactus, C4 Picasso, C4 SpaceTourer, C5 Aircross, Jumpy, SpaceTourer |
| Cupra | Formentor, Leon |
| DS | 3, 7 Crossback, 9 |
| Fiat | Ducato, Scudo |
| Ford | EcoSport, Focus, Kuga, Puma, Tourneo Connect, Transit Connect, F-250, F-350, F-450 and F-550 Super Duty |
| Ford Trucks | F-650 Super Duty |
| Genesis | G70, G80, GV70, GV80 |
| Hyundai | Palisade, Porter, Starex, Staria |
| Iveco | Daily |
| John Deere | 5G Series |
| Kia | New Bongo, Sorento, Stinger, Tasman |
| Land Rover | Defender, Discovery, Range Rover, Range Rover Sport, Range Rover Velar |
| Landini | 5-Series, 6-Series tractors |
| Massey Ferguson | MF 3xx |
| McCormick | X5.085, X5.100, X5.110, X5.120, X6.125, X6.135 |
| New Holland | T4 Series, T4 Powerstar Series, T5 90, T5 100, T5 110, T5 120, T5 Series |
| Opel | Astra, Combo, Corsa, Crossland X, Grandland X, Mokka, Vivaro, Zafira Life |
| Peugeot | 208, 2008, 308, 3008, 508, 5008, Expert, Partner, Rifter |
| Porsche | Cayenne, Cayenne S, Cayenne E-Hybrid, Cayenne S E-Hybrid, Macan, Macan S, Macan GTS, Macan Turbo, Panamera, Panamera 4, Panamera 4S, Panamera 4 E-Hybrid, Panamera 4S E-Hybrid |
| SEAT | Ateca, Leon, Tarraco |
| Secma | F16 Turbo |
| Skoda | Karoq, Kodiaq, Octavia, Superb, Yeti |
| Steyr | Kompakt |
| Toyota | Proace City |
| Vauxhall | Astra, Combo, Corsa, Crossland X, Grandland X, Mokka, Vivaro, Zafira Life |
| Volkswagen | Arteon, Caddy, Golf, Passat, Polo, Talagon, Tiguan, Touareg, T-Roc |
If your vehicle is on this list and it was built from 2021, the unlock no longer means posting the unit away. If it is not, that does not mean nothing can be done, only that yours takes the established route. Tell us the make, model, engine and year either way.
BMW, Mercedes and others
BMW and Mercedes are not on this coverage list, and neither is Jaguar or Mini. They use engine ECUs from the same protected Bosch family, which is why they have the same locked-unit problem, but this particular unlock does not reach them.
For those, a locked unit still goes the established route of coming out and being sent away. Work is ongoing on that side and we would expect coverage to widen before long, which is the pattern these releases usually follow. Tell us the model, engine and year and we will tell you exactly where yours stands today.
How the unlock actually happens
It is boot mode work. The ECU comes out of the vehicle, the casing comes off, and the tool connects directly to pads on the circuit board. That is the deepest of the three ways into an ECU, and it is what these units require.
Our OBD, bench and boot mode guide compares the three routes if you want the background.
If you were told no before
This is the part worth acting on. If you asked about tuning a 2021-or-newer vehicle in the last couple of years and were told it was not viable, or were quoted separately for an unlock and decided against it, that answer may well have changed.
Send us the make, model, engine and year. We will confirm whether your ECU is covered, what it needs, and what is realistic for that engine.
Frequently asked
What does a locked ECU mean?
Protected ECU software is not new. What is specific about the Bosch MDG1 units is that they held out against the tuning tools far longer than most, so a run of 2021-onward vehicles sat in the "has to be sent away" category for years. An unlock is the one-off step that opens the unit up for reading and writing.
Does the ECU still have to come out of the car?
Yes. The unlock is boot mode work, so the unit is removed and opened for the tool to connect to the board. What has changed is that it no longer gets posted to a third party, so it is one visit rather than a multi-day round trip.
Is my BMW covered?
Not by this one. BMW uses ECUs from the same protected Bosch family but is not on this coverage list, and neither is Mercedes, Jaguar or Mini. A locked unit on those still goes the established route for now. Work is ongoing and we would expect coverage to widen before long, so ask about your specific vehicle.
How do I know which ECU my car has?
You do not need to. Tell us the make, model, engine and year and we will identify the unit and tell you what it needs before you book.
My car has already been tuned. Does that matter?
It can. Some of these units are handled with a virtual read, where the original file comes from a database rather than off your car, so previous work is replaced rather than preserved. Mention it when you get in touch.
Which manufacturer do you drive?
Every map is written for your exact make, model and engine. Pick yours to see the models we work on most.
Mobile remapping across the South West
We come to you across Weston-super-Mare and the towns right across the region. A few of the areas we cover:
Ready to transform the way you drive?
Call 01934 245246 · info@carbontuning.co.uk