VW / Audi / Seat / Skoda (VAG) Bosch MA1.2.2 Engine ECU Repairs

Type: Bosch Engine Management
Fits: VAG – Audi / Seat / Skoda / Volkswagen (VW)
Fuel: Petrol
Ref: ECUT191195

Note: This ECU may also fit other models.

Naming the car does not get you to the right MA1.2.2. The references covered on this page are all documented against the same two Volkswagens, and settling on the 1.8 rather than the 1.4 still leaves four separate control units answering to the description.

What separates them is the ten-digit Bosch number on the case. What follows sets out which reference goes with which engine, what the letter on the end of the Volkswagen Group number is and is not doing, and how a unit of this age is repaired.

The suffix letter changes; the car does not

Read down the Volkswagen Group column of the table at the foot of this page and the letters move constantly. On one base number they run C and K. On the other they run C, F, H and L. Behind them, the car does not move at all.

Both 030 906 026 references are documented against the Volkswagen Golf III and the Vento with the 1.4-litre petrol engine. All four 1H0 907 311 references are documented against the same two cars with the 1.8. Across the references covered here, the letter is marking a revision of one control unit built for one application — it is not pointing at a different car, a different badge or a different engine.

The practical consequence is that working out you have a 1.8 Golf III narrows the field to a base number and then stops. Four units answer to it, and the reference that tells them apart is the Bosch number.

That has a second consequence worth knowing. Because the letters are revisions inside one application rather than variants for different cars, a reference quoted with the letter guessed or left off will still look right against the vehicle: same model, same body, same engine size. Nothing about the car contradicts it. The ten-digit Bosch number is the only reference on the unit that will.

Both 030 906 026 references are the 1.4

030 906 026 C is Bosch 0261200257. It appears on records for the Golf III (1H1) and for the Vento (1H2) with the 1.4-litre engine, and a UK trade catalogue files it as a Mono-Motronic unit built for a Golf between 1990 and 1992.

030 906 026 K is Bosch 0261200750, and the records put it on the same job: a Golf III with the same 1.4-litre engine. Two references, one car, one engine, and the only thing that changes between them is the letter.

That is worth being blunt about, because it is the trap on this designation. Establishing that the car is a 1.4 Golf III does not choose between these two. Only the ten-digit Bosch number does.

All four 1H0 907 311 references are the 1.8

1H0 907 311 C is Bosch 0261200714. Used-parts records list that pair of numbers under the Golf III and under the Vento (1H2) alike, always with the 1.8.

1H0 907 311 F is Bosch 0261200760 and 1H0 907 311 H is Bosch 0261200784. A UK trade catalogue files both as Mono-Motronic units for the 1.8 Golf of 1992 to 1993 — two entries, two suffix letters, one car and one engine between them.

The fourth is 1H0 907 311 L, which is Bosch 0261203318. The records for it are consistent and plentiful: a Golf III (1H1) or a Vento, 1.8 petrol, the same unit again under one more letter.

Four references, one engine, one pair of cars. C, F, H and L are marking successive versions of a control unit that was built for a single application, which is why looking at the car will never reach any one of them.

The base number does not even settle which system you have

030 906 026 is not exclusive to the MA1.2.2. The same base number carries MA1.2.1 units: 030 906 026 A is Bosch 0261200253 and 030 906 026 B is Bosch 0261200259, and both are documented as MA1.2.1 control units for the Volkswagen Polo.

So a reference written down as 030 906 026, with the letter dropped, does not identify the unit and does not even identify the system. The letter settles which family you are in; the Bosch number then confirms it. An A or a B on that base is an MA1.2.1, not an MA1.2.2, and we set the MA1.2.1 references out separately.

The letter is not doing nothing, then. Across the MA1.2.2 references on this page it separates revisions of one unit; widen the base number beyond this page and it separates one Bosch system from another. What it never does on this designation is tell you which car.

What a Bosch MA1.2.2 is, and why it reaches beyond Volkswagen

The MA1.2.2 is a Bosch Mono-Motronic system: fuel and ignition managed by one control unit, with single-point injection — a single injector sitting above the throttle body and feeding the whole inlet manifold, rather than one injector per cylinder. Published trade catalogues file the MA1.2.2 as a 45-pin system, and give that same description against several of the references here.

Because the designation groups units by the injection system they manage, it is not a Volkswagen-only label. MA1.2.2 units are documented on the Seat Ibiza and the Cordoba with the 1.3-litre petrol engine, on a reference from this same 030 906 026 family. None of those is on this page: every reference covered here is a Volkswagen, and they sit with the rest of the Volkswagen engine ECUs on our bench.

If you are holding an MA1.2.2 that came off a Seat, the system is right and the reference is not on this page; our engineers will confirm coverage for a specific unit rather than guess at it.

How these units are repaired

A failed MA1.2.2 is repaired at component level rather than exchanged. The unit is logged in, inspected and put on test before any work is proposed; the diagnosis then works down to the specific parts on the board that have failed, and those are replaced under a microscope with temperature-controlled rework equipment. Nothing leaves until it has passed final testing.

That work is carried out by our own engineers, in our own UK workshop, with nothing subcontracted and nothing sent overseas. We test and diagnose first and come back to you with what has failed and what the repair will cost; no chargeable work starts until you have authorised it. Price is on application, and every repair carries a 24-month warranty on the work done.

It is a mail-in service, wherever in the UK you are. Have both references to hand when you get in touch — the ten-digit Bosch number and the Volkswagen Group number, letter and all — and book it in through the Repair Form.

The part-number listing for this designation follows.

Common part numbers associated with this type of unit