Ford Siemens SIM 20 Engine ECU Repairs

Type: Siemens Engine Management
Fits: Ford
Engines:
Year:
Fuel: Petrol
Ref: ECUT20175

Note: This ECU may also fit other models.

D, E and G are what separate the three rows of our Siemens SIM20 table. Each is the last letter of a Ford number, and on the labels our sources describe, the same letter usually appears a second time, at the end of the Siemens number printed alongside it. Reading it in both places is the quickest way to your row, and the sections below explain how, then what to send once you have found it.

Three Ford numbers, one car on record

Our table lists three Ford numbers: 1S6A-12A650-AD, 1S6A-12A650-AE and 1S6A-12A650-AG. Taken together, the SIM20 numbers in our table are on record from the petrol Ford Fiesta 1.25. Taken one at a time, each is on record from a Ford Fiesta, AD from ten independent sources, AE from seven and AG from eight.

That makes this table a sensible place to start. It does nothing to choose between the rows, because a Fiesta badge is equally consistent with all three. The model name can bring you to this table, but it stops there; the letters are what finish the search.

The same letter, printed twice

On the labels described in our sources, the Siemens number beside each Ford number usually closes with the same letter as the Ford number. 1S6A-12A650-AD is printed alongside S110678003 D, AE alongside S110678003 E, and AG alongside S110678003 G, in nine, nine and eleven independent sources respectively.

That gives you a check that works in either direction. A label reading S110678003 D belongs with 1S6A-12A650-AD, so if the Ford number has been scuffed or covered, the letter at the end of the Siemens number still points you to a row. Where both numbers are legible, expect the two letters to agree; if yours do not, send us both exactly as printed and mention it.

Where our table leaves the letter off

Our own table does not carry that check all the way through. On the AD and AE rows it prints the Siemens number as S110678003, with no closing letter. Only the AG row prints it in full, as S110678003G.

On those two rows, then, the Siemens number in the table is identical and cannot separate them. The Ford number can, which makes it the safer match for AD and AE. Your label may well show the letter our table omits, so copy the Siemens number complete rather than trimming it to look like the entry below.

Extra print after the Ford number

Some labels carry a further code after the Ford number. Our table shows one, J38AC, printed on the AD row. The same code is recorded beside the other two Ford numbers as well, so it cannot pick out a row by itself, and we do not use it that way.

Send it anyway, with every other line of print you can read. We would rather set aside a code that turns out not to matter than ask you for one after the unit has arrived.

What happens to a SIM20 unit on our bench

Garages and owners anywhere in the UK post their units to us; there is no counter service, by design. Our own engineers do the work in-house. Each unit is logged when it arrives, inspected, tested electrically and then diagnosed against the fault you describe.

Repairs to the board are made at component level, under a microscope and with temperature-controlled rework equipment. The unit stays with us until it passes a final test.

Before any chargeable work starts, we report what testing found and quote for the repair, and nothing goes ahead without your agreement. The work we carry out is covered by a 24-month warranty.

Sending a SIM20 unit to us

When you send us every line of that label, give the Ford number and the Siemens number with their closing letters, plus any extra code such as J38AC. Add the model the unit came from and what the car was doing when the fault started.

If your Ford number is not one of the three here, the unit may belong on another page. Siemens SIM210 units from Ford are listed separately, and the Ford section of our library covers the make’s other engine ECUs. If the car is another make altogether, look at engine ECUs from beyond the Ford range.

Below, each of the three Ford numbers, printed without hyphens, sits beside the Siemens number our table prints for it.

Common part numbers associated with this type of unit