VW / Audi / Seat / Skoda (VAG) Siemens Simos 3 Engine ECU Repairs

Type: Siemens
Fits: VAG – Audi / Seat / Skoda / Volkswagen (VW)
Fuel: Petrol
Ref: ECUT217195

Note: This ECU may also fit other models.

A Volkswagen Fox 1.2 is recorded against a single Simos 3 reference on this page. A Polo 1.2 is recorded against six. Every other car covered here falls somewhere between those two, and where yours falls tells you how much work the part number on the label has to do.

Simos is a family of Siemens engine ECUs. The Simos 3 units described below come from petrol Volkswagens, Audis, Seats and Skodas with 1.2, 1.4, 1.6 and 2.0 engines, and we repair them at component level in our own UK workshop. This page sorts those cars by how many references each is recorded against, and treats that number as a guide to how closely the unit in your hand needs checking.

Cars recorded against one Simos 3 reference

Five cars here, one of them a Skoda 1.6 with no model named, are each recorded against one reference and no more. For these, the car and the label should agree at the first look.

The Volkswagen Fox 1.2 is recorded against 03D 906 033 H, with the BMD engine. The Volkswagen Polo 1.6 is recorded against 036 906 033 D, and the Seat Ibiza 1.6 against 6K0 906 033 B, with the AUR engine.

Two more come with less detail attached. 06A 906 033 AF is recorded in the Volkswagen Bora, and the records we accept stop at the car without settling the engine size. 06A 906 033 BG is recorded against that Skoda 1.6, and we go no further than that.

One reference on this page is not the same as one reference in existence. It means that among the units described here, only one has been documented in that car. If the number on your Fox, Polo 1.6 or Bora is not in the table at the foot of the page, the unit may belong to another engine ECU family, and the Volkswagen models listed under other engine ECUs are the next place to look.

Two to four references: Fabia 1.4, A3, Golf, New Beetle and Passat

None of these cars is recorded against more than four references, and on each car the references share one base, so the letters at the end do the separating.

The Skoda Fabia 1.4 has two: 047 906 033 C and 047 906 033 H. They are the only 1.4 units on this page and the only references on the 047 base.

The Audi A3 1.6 has three: 06A 906 033 BD, J and N. The records attach an engine code to one of them, the AVU on J, and for BD and N they give the car and engine size only. If the number on an A3 is none of these, see A3 owners whose label differs.

The Golf 1.6 has four. The unsuffixed 06A 906 033 is recorded in the Golf 4 1.6 with the APF engine, and 06A 906 033 AJ and M in the Golf 4 1.6. 06A 906 033 BL is recorded in the Golf 1.6 against two engine codes, the AZD and the BFQ.

The New Beetle is also recorded against four on the same 06A 906 033 base. AK, BP and DP are recorded as New Beetle 1.6 units. L is recorded in the New Beetle without an engine size we can confirm, so we leave it at the car.

The Volkswagen Passat 2.0 has four as well, and they are the only 2.0 units on the page: 06B 906 033 AA, G, H and T. AA is the one the records place in the B5 Passat.

At this level the car gets you to a short list of numbers that differ only in their last one or two characters.

Four apiece on the small cars: Fabia 1.2 and Ibiza 1.2

The 1.2 is where this page gets crowded. Fifteen of the thirty-six references described here come from 1.2 cars, across the Polo, Fabia, Ibiza and Fox.

The Skoda Fabia 1.2 is recorded against four: 03D 906 032 A, 03D 906 033 C, 03E 906 033 A and 03E 906 033 AB. Those four sit on three different bases, so on a Fabia 1.2 the start of the number matters as much as the letters at the end. Two of them, 03D 906 032 A and 03E 906 033 A, even end in the same letter. For any other Skoda, or a Fabia number not shown here, find your Skoda by model.

The Seat Ibiza 1.2 is also recorded against four, all on 03E 906 033: AA, AM, D and P. D and P are both recorded with the AZQ engine; for AA and AM the records stop at the Ibiza 1.2. For an Ibiza whose number is not on this page, look through Seat units carrying a different number.

Here, unlike on the Fabia, the base does no separating at all. Among these four Ibiza references, the suffix is the only part of the number that differs.

Six on one car: the Volkswagen Polo 1.2

The Polo 1.2 is the most crowded car on this page. Six references are recorded against it, and they sit on three bases.

Two are on the 03D bases: 03D 906 032 C is recorded with the AWY engine, and 03D 906 033 F with the BMD. The other four are on 03E 906 033. The unsuffixed number and 03E 906 033 L are both recorded with the AZQ engine, 03E 906 033 R is recorded as a 12-valve, and 03E 906 033 AK as a Polo 1.2 with nothing further attached.

Add 036 906 033 D from the Polo 1.6 and the Polo accounts for seven references here, more than any other car. For a Polo owner, the model name gets you onto the page and the part number does the rest.

Engine codes narrow it only so far. The AZQ is recorded on two Polo references and two Ibiza ones, and the BMD on a Polo and a Fox, so a code shared between cars cannot pick out one unit by itself.

What the count means before a unit goes in the post

The count measures how much checking the label needs. On a car with one reference, the check is a confirmation. On a car with six, the check is the identification itself, and it has to run to the last character.

The suffix on its own is not enough either. Several suffixes repeat on this page under different bases: AK is a Polo 1.2 reference on 03E 906 033 and a New Beetle 1.6 reference on 06A 906 033; AA is an Ibiza 1.2 on one base and a Passat 2.0 on another; H turns up on a Fox 1.2, a Fabia 1.4 and a Passat 2.0. Quote the whole number, base and suffix together.

The base offers a rough cross-check. In the records behind this page, the 03D and 03E bases belong to 1.2 cars, 047 to the 1.4, 036, 06A and 6K0 to the 1.6 cars (the Bora and one New Beetle reference aside, where no size is recorded), and 06B to the 2.0. That is a pattern in these references, not a rule for reading any VAG number, and it does not replace the full number.

None of this says which unit will run which car. An engine code shared between two cars, or a suffix repeated across bases, is a record of what has been documented, not grounds for fitting one unit in place of another. We identify each Simos 3 from its own label, read against the car it came from, and the repair is made to the unit you send rather than to a substitute.

Having a Simos 3 repaired in our UK workshop

Our workshop repairs engine ECUs only, and every Simos 3 that arrives is handled by our own engineers on site. Each unit is booked in and inspected on arrival, tested electrically, and then diagnosed for its specific fault.

The repair is carried out at component level on the part that has failed, under a microscope and with temperature-controlled rework equipment. A unit is only finished once it passes final testing.

After diagnosis we come back to you with what we found and a quote, and no chargeable work starts until you give the go-ahead. The repair carries a 24-month warranty.

The service works by post, for owners and garages anywhere in the UK. When you are ready, put the full reference, suffix included, on the Repair Form, together with the car and its engine size. If the car is not a Volkswagen, Audi, Seat or Skoda, our page for makes outside the VAG group is where to start.

Every row for this page is in the table below, including six references not described above. If yours is one of those, quote it on the form and our engineers will confirm whether we cover it before the unit comes out of the car.

Common part numbers associated with this type of unit