VW / Audi / Seat / Skoda (VAG) Bosch M3.8.3 Engine ECU Repairs

Type: Bosch Engine Management
Fits: VAG – Audi / Seat / Skoda / Volkswagen (VW)
Fuel: Petrol
Ref: ECUT185195

Note: This ECU may also fit other models.

06A 906 018 R and 071 906 018 R both appear in the table at the foot of this page, and they are not the same control unit. They carry different Bosch numbers — 0261204673 and 0261206176 — and they were built for different engines. The letter the two share tells you nothing about either of them.

What separates them is the group at the front of the VAG number, and the front is the part that gets dropped. What follows sets out what each reference below is documented against, and which numbers are worth quoting when a unit comes in.

The prefix is what tells the two engines apart

Every VAG reference on this page opens with one of two groups. The ones that begin 06A 906 018 are four-cylinder units — 1.8, 1.8 turbo and 2.0. The ones that begin 071 906 018 are the 2.3 V5. One designation, one page, two unrelated engines.

The trailing letters do not separate the two groups. Table 185 carries 06A 906 018 R and 071 906 018 R, and the R is all those two references have in common: two Bosch numbers, two engines, one letter.

A suffix on its own therefore identifies nothing here. Read whole, a reference on this page is unambiguous; read back from the letter, it sits somewhere between a 1.8 turbo Golf and a 2.3 V5 Passat.

The mix-up is already in circulation

One UK listing offers an engine ECU for a Golf MK4 2.3 with the AGZ engine, gives the Bosch number correctly as 0261206176, and then gives the VAG number as 06A906018R — the four-cylinder prefix, on a V5 unit.

Every other record for 0261206176 gives 071 906 018 R, including a UK trade catalogue that files it as Bosch Motronic M3.8.3 against a Golf with the 2.3 AGZ engine. The error is the one the numbering invites: the suffix travelled and the prefix did not. And it cuts both ways — a genuine 06A 906 018 R off a 1.8 turbo looks wrong against a listing like that one.

The 06A references: 1.8, 1.8 turbo and 2.0

Ten of the fourteen references open 06A 906 018, across the Golf IV, Bora, Audi A3 and Skoda Octavia.

The AGU 1.8 turbo accounts for the largest share. 0261204673 (06A 906 018 R) is documented against the Golf IV 1.8T at 150 hp. 0261204678 (06A 906 018 AQ) is the Audi A3 1.8T, same engine code, same output. 0261206516 (06A 906 018 CJ) is the A3 1.8T again, and appears on Volkswagen listings too.

Three more references reach the Skoda Octavia. 0261206517 (06A 906 018 CH) and 0261206518 (06A 906 018 CG) are both documented against the Golf IV 1.8T and both are sold against the Octavia 1.8T; 0261206520 (06A 906 018 GB) is documented against the Octavia with the AGU engine and filed by some catalogues under Volkswagen. Octavias of that generation are a routine part of the Skoda engine ECU repair we do.

That leaves four. 0261204800 (06A 906 018 BB) is documented against the Golf IV 1.8, and a trade catalogue puts it on the AGU engine. 0261206127 (06A 906 018 BM) is the Audi A3 1.8, engine code AGN. 0261206324 (06A 906 018 EF) is the Golf IV and Bora 2.0 at 115 hp, engine code APK. 0261206260 (06A 906 018 FL) is the Golf IV and Bora as well, though the records disagree on the engine.

The 071 references: the 2.3 V5

Four references open 071 906 018, and every one of them is documented against the 2.3-litre V5 with the AGZ engine code.

0261204753 carries the bare 071 906 018 with no suffix at all, documented against the Golf 2.3 V5. 0261206175 (071 906 018 K) has the fullest record of the four: a UK trade catalogue lists it as Golf, AGZ, 2.3 litre, 97–01, Bosch Motronic M3.8.3, OEM reference 0 261 206 175, manufacturer reference 071 906 018 K, and other listings put the same reference on the Seat Toledo and the Bora 2.3. 0261206165 (071 906 018 P) is the Passat 2.3 V5. 0261206176 (071 906 018 R) is the Golf and Bora 2.3, and is the row the mislabelled listing belongs to.

The designation is softer than it looks

M3.8.3 is not much of an identifier on its own either. The same Bosch numbers on this page are filed by different catalogues under M3.8.3, under M3.8.5, and under a combined M3.8.2 / 3.8.3 / M5.9.X heading; one of them a trade catalogue files as M5.9.2. The listing that gave 0261206176 the wrong prefix filed it as M3.8.5, while the same seller files 0261206175 as M3.8.3.

That is not a criticism of anyone’s cataloguing, but it is a reason to identify a unit from the numbers on it rather than the family name — and, where the VAG number is one of them, to read it from the front.

What to quote when you send one in

Quote the ten-digit Bosch number from the label, in full. If the VAG number is legible, quote all of it — the 06A 906 018 or 071 906 018 group as well as the letters after it. The car and the engine help as a cross-check, not as the identifier: a Golf IV on its own covers more than half the references above.

One thing that catches people out: a few listings print these units with 997 in the middle group where our table has 906. Send the number exactly as it reads on your unit.

The work is done in our own UK workshop by our own engineers, and nothing is sent elsewhere. A unit that arrives is logged, inspected and electrically tested, then taken through fault-specific diagnostics; board-level work is carried out under a microscope with temperature-controlled rework equipment, and it is not finished until it has passed final testing. The unit that goes back is the one that came out, and the repair carried out is covered by a 24-month warranty.

We work by post, across the whole of the UK. Give us the Bosch number, the VAG number if you have it, and the car — the Repair Form is the place to put them. The unit is tested and diagnosed first, so you know what has been found before any chargeable work begins. If the reference on your label is not among the fourteen below, it is still worth asking: other Volkswagen engine ECU part numbers we hold run well beyond this designation.

Common part numbers associated with this type of unit