VW / Audi / Seat / Skoda (VAG) Siemens Simos Engine ECU Repairs

Type: Siemens
Fits: VAG – Audi / Seat / Skoda / Volkswagen (VW)
Fuel: Petrol
Ref: ECUT215195

Note: This ECU may also fit other models.

Four vehicles between them cover almost everything the early Siemens Simos list has to say: a Volkswagen T4 Transporter 2.5, a Golf 3, a Sharan and a Seat Cordoba 1.6. Run each one against the part numbers and you see how the references divide, where a single letter settles the car and where the public record stops. We repair every unit described below, at component level, in our own UK workshop.

The part-number table at the end of this page lists nineteen references. Fifteen of them can be placed in a vehicle from the public record, and those fifteen sit on three bases: 023 906 025, 037 906 025 and 6K0 906 025. Among the fifteen, no vehicle turns up on more than one base, so the vehicle tells you which base to look under and the final letter does the rest. The other four are in the table; if yours is one of them, ask us rather than guess.

A T4 Transporter 2.5: two references on a base of its own

Start with the van, because it is the simplest case. The T4 Transporter 2.5 has its own base, 023 906 025, and nothing else on this page shares it. Two references sit there: 023 906 025 with no letter after it, and 023 906 025 C. Both are recorded in the T4 2.5, and the record for the C also names the five-cylinder engine.

So the question a T4 owner has to answer is a small one: is there a C after the base or not? Read it off the label on the unit itself. A reference that ends at 025 is valid in its own right, since 023 906 025 appears in the list exactly like that, so write it down as it reads rather than assuming a letter is missing.

A Golf 3: the engine size first, then the letter

The Golf 3 is the busiest vehicle on the page. Seven of the fifteen described references are recorded in one, all on the 037 906 025 base, and the Golf’s engine size divides them before any letter does. Two are 1.6 units and five are 2.0 units, and no letter is recorded under both sizes.

On a 1.6 Golf 3 the choice is between J and T. The record for 037 906 025 J names the AKS engine. The record for 037 906 025 T describes the 1.6 as an 8-valve, and T has also been recorded in a Golf 3 Cabriolet. The car and the engine size take you this far and no further; the letter on the label separates them.

A 2.0 Golf 3 has five candidates: A, G, H, P and R. Only R carries an engine code in the record, the AGG, and only G is also recorded in another model, the Passat 2.0. A, H and P are recorded simply as Golf 3 2.0 units, so neither the car nor the engine size will choose between them. The label has to.

If you have come to this page with a Passat 2.0 rather than a Golf, G is the reference here with a Passat recorded against it. If your label shows another letter on the 037 906 025 base, send us the full reference and our engineers will confirm it before anything is posted.

If your Volkswagen’s label starts with a base that appears nowhere in the table below, the unit is not one of these; the wider Volkswagen picture is the place to look.

A Sharan: the Golf’s base, with a Seat alongside

The Sharan is the odd one out in the 037 906 025 group: a very different Volkswagen on the same base as the Golf. The reference recorded in the Sharan 2.0 is 037 906 025 B, and its record names the ADY engine.

A Seat sits on the same base too: 037 906 025 S is recorded in a Seat Alhambra. Treat the two as separate references, each with its own badge: B is the one recorded in a Sharan, S the one recorded in an Alhambra.

What the Sharan example shows is that on 037 906 025 the base alone tells you little about the vehicle. A Golf, a Passat, a Sharan and an Alhambra all share it, and the letter is where they part company.

A Seat Cordoba 1.6: one engine code across four cars

The third base, 6K0 906 025, is where Volkswagen and Seat meet. Three of its four described references are recorded with the 1.6 AFT engine, across the Polo and three Seats. A Cordoba 1.6 AFT has two candidates: 6K0 906 025 with no letter, recorded in the Polo and the Cordoba, and 6K0 906 025 E, recorded in the Polo, the Ibiza and the Cordoba.

So a Polo 1.6 AFT arrives at the same two candidates as the Cordoba. The Toledo 1.6 with the AFT engine has a reference to itself, 6K0 906 025 A.

For an Ibiza, the E is the AFT reference the record places in one. Separately, 6K0 906 025 D is recorded in a Seat Ibiza. An Ibiza owner therefore has two references on this base to compare with the label, E and D.

For a Seat whose label matches nothing in the table below, there is a fuller account of Seat engine ECU repair.

How we carry out a Siemens Simos ECU repair

Whichever vehicle your unit came from, the repair is done in-house by our own engineers in our UK workshop. Each unit is logged, inspected and electrically tested, then taken through diagnostics aimed at the fault it arrived with. Component-level work is carried out under a microscope with temperature-controlled rework equipment, and the repair is not finished until the unit passes its final test.

Because we repair the fault rather than supplying a different unit, the reference you read off the label is still the reference on it when it comes back. We contact you with what we found and what the repair involves, and no chargeable work starts until you have agreed to it. The repair carries a 24-month warranty.

The service is mail-in across the UK. When you fill in the Repair Form, give us the vehicle, its engine size and the full reference from the label, the same three things each example above was worked from: make yours the fifth worked example.

For any other make, begin with the complete set of engine ECUs we repair.

Every reference discussed on this page, together with the four not described above, is listed below.

Common part numbers associated with this type of unit