VW / Audi / Seat / Skoda (VAG) Bosch MA1.2.3 Engine ECU Repairs

Type: Bosch Engine Management
Fits: VAG – Audi / Seat / Skoda / Volkswagen (VW)
Fuel: Petrol
Ref: ECUT192195

Note: This ECU may also fit other models.

030 906 026 AB is printed against two different Bosch references in the table at the foot of this page. So is 3A0 907 311 B. Neither repetition is an error, and between them they show how the whole list is put together.

These references run in consecutive pairs, and a pair is one control unit. 0261203650 and 0261203651 are one; 0261203788 and 0261203789 are another; and the Volkswagen Group number belongs to the pair rather than to either number on its own. Read the rest of the list that way and five further references on this page can be put to a vehicle-manufacturer number and a car.

Why two Bosch numbers share one Volkswagen Group number

The pairing is stated twice in the table itself, which is the strongest evidence for it there is: 0261203650 and 0261203651 both carry 030 906 026 AB, and 0261203788 and 0261203789 both carry 3A0 907 311 B. Used-parts and remanufacturing records for those same two units write them as single items — 0 261 203 650/651 and 0 261 203 788/789 — with one Volkswagen Group number against each.

The same convention runs through the rest of the designation. Outside records quote 0 261 203 184/185, 0 261 203 186/187, 0 261 203 302/303 and 0 261 203 647/648 in exactly that form, each with a single Volkswagen Group number for the pair.

So if the number on the case is the second of a pair, the vehicle-manufacturer reference you need is the one carried by the first. Every pairing below is corroborated by outside records as well, not inferred from the sequence on its own.

An Audi number on a Golf: the 8A0 907 311 references

Three vehicle-manufacturer numbers on this page share the 8A0 907 311 base, and they are not all the same marque.

0261200735 is 8A0 907 311 B. The records for it agree closely: an Audi 80 (B4), 2.0 petrol.

0261203184 is 8A0 907 311 H, and 0261203185 is the other half of that pair — the same unit under the same vehicle-manufacturer number. Both are documented against the Volkswagen Golf III with the 1.8-litre petrol engine.

0261203186 is 8A0 907 311 M, with 0261203187 as its pair. That one is a Golf III 1.8 as well.

So anyone who has taken a control unit out of a Golf and read an Audi part number off the label has not got the wrong unit. The 8A0 base records where the reference was filed; it does not say which car the unit sits in. On this page it covers one Audi and two Volkswagens.

The 3A0 907 311 references, on a Golf and on a Passat

Two vehicle-manufacturer numbers here share the 3A0 907 311 base, and they run the other way about.

0261203593 is 3A0 907 311, with nothing after the last digit, and 0261203594 is its pair. The records place that unit on the Golf III with the 1.8.

0261203788 and 0261203789 are 3A0 907 311 B, the same base with a B added, and that unit is documented on the Passat B3 and B4, again with the 1.8.

Two things follow. The base is not a model line: here it covers a Golf and a Passat, exactly as 8A0 907 311 covers an Audi and two Volkswagens. And the letter on the end identifies nothing by itself — 8A0 907 311 B is the 2.0 Audi 80 in the first row of the table, and 3A0 907 311 B is the 1.8 Passat near the end of it. Same letter, different base, different car, different engine.

The 030 and 032 references: the 1.4s and the 1.6s

0261203302 is 030 906 026 R, with 0261203303 as its pair. The records give a Golf III, 1.4-litre petrol.

0261203650 and 0261203651 are 030 906 026 AB, the first of the two pairs the table carries in full. A Golf III 1.4 again.

0261203304 is 032 906 026 E, a Golf with the 1.6.

0261203647 is 032 906 026 G, with 0261203648 as its pair. Golf III, 1.6.

Across those four, the 030 906 026 references are the 1.4s and the 032 906 026 references are the 1.6s. It is worth noticing and it is worth not leaning on: it is a pattern in these particular records, not a rule you can identify a unit by. The reference on the case is what settles that. All four are Volkswagens, and the MA1.2.3 is one of the Bosch designations we cover in repairing Volkswagen engine ECUs.

What the records will not settle

Not every reference on this page can be tied to a vehicle-manufacturer number and a car, and the gaps would be easy to fill by guesswork. We have not filled them.

For most of the remaining references the public record is either silent or too thin to use. One example: a single listing puts 3A0 907 311 A against 0261203591. One listing is not enough. Every vehicle-manufacturer number set out above is given by more than one unconnected record, and that is the standard the rest have to reach before they appear here.

Where the record does say something, it does not always agree with itself. Both of the sources that mention 0261203752 and 0261203753 write them as a pair, so the pairing holds — but one files that pair under a 1.6 Volkswagen and the other under a 1.6 Seat. The pair is settled; the car is not.

None of that stops a unit being repaired. The reference is read off the case, the board is inspected and put on test, and what the unit is gets established from the unit rather than from a list. If the label reads MA1.2.2 rather than MA1.2.3, you want the MA1.2.2 part-number list instead.

Sending a Bosch MA1.2.3 in for repair

The MA1.2.3 is a Bosch Mono-Motronic unit — one control unit managing fuelling and ignition on a single-point petrol engine.

These are repaired at component level rather than exchanged. A unit is booked in, visually inspected and then tested electrically to establish where the fault actually sits; the failed parts are replaced on the board under a microscope, with temperature-controlled rework equipment, and the unit is tested again before it is signed off. Because the fault is fixed on the original board, nothing on the unit is reprogrammed and its coding stays as it was.

All of that happens in our own UK workshop, on our own equipment, by engineers we employ — no part of it is subcontracted or sent abroad. You are told what has failed and what putting it right will cost before anything is charged for, and the repair is covered by a 24-month warranty. Price is on application.

Engine control units are the whole of what we repair — engine ECU repair, across every make we cover — and it works by post, anywhere in the UK. Quote both numbers when you get in touch, the ten-digit Bosch reference and the Volkswagen Group number with its letter; if neither is on this page, our engineers will confirm coverage for that specific unit rather than guess at it. Send it in with the Repair Form.

The full reference list for this designation is below.

Common part numbers associated with this type of unit