Ford Siemens SIM 28 Engine ECU Repairs

Type: Siemens Engine Management
Fits: Ford
Engines:
Year:
Fuel: Petrol
Ref: ECUT25175

Note: This ECU may also fit other models.

Copy the Ford number from a SIM28 label right through to its last character. In our table it is often the only thing separating one Ford number from the next, and on every pairing on record it turns up again at the end of the matching Siemens number.

Three letters at the end, not two

Most Ford numbers in our SIM28 table close with two letters, as 4M51-12A650-HG does. The four that begin 7M51 close with three: 7M51-12A650-AFA, AFB, AGA and AGC.

Stop at two and you are left with AF or AG, each of which leads to two rows. The third letter is what separates AFA from AFB and AGA from AGC, so copy all three.

Our table prints each Ford number without its hyphens, as 7M5112A650AFA 2GMA. Most Ford numbers carry a short extra code after them, like the 2GMA there, and our table prints one on nearly every row. Bring that code across from your label too, character for character, whether or not our table shows one against your number.

The Siemens letter as a cross-check

The Siemens numbers in our table all begin S118934, followed by three more digits and, on the label, a closing letter. On every pairing on record, that letter echoes the last letter of the Ford number: S118934002 F with 3M51-12A650-FF, S118934105 A with 4U71-12A650-LA and S118934104 B with 5M51-12A650-ZB.

Among the 7M51 numbers the echo picks up the third letter: S118934202 A goes with 7M51-12A650-AFA and S118934202 B with AFB, while S118934203 A pairs with AGA and S118934203 C with AGC. It holds just as well for 5M51-12A650-FG, on record with S118934102 G, and 5M51-12A650-GC, on record with S118934103 C.

The echo is a cross-check drawn from the pairings on record here, not a rule beyond them. When both numbers are legible and their last letters agree, that is good evidence you are on the right row. If they do not agree, copy both exactly as printed rather than adjusting either one to fit.

Where our table prints a Siemens number with no letter, or no Siemens number at all, expect a lettered Siemens number on your label. On those rows the Ford number makes the match.

Seven Ford numbers on one Siemens base

S118934101 is the Siemens base for seven of the Ford numbers in our table, 4M51-12A650-HB, HC, HD, HE, HF, HG and HJ, and only its closing letter tells one from the next. Read the base on its own and you have narrowed the table to seven rows without choosing between them.

That is why the Ford number is the safer match here, with the Siemens base and its letter as the check. The pairings on record are S118934101 B with HB, C with HC, E with HE, F with HF and G with HG, and our table prints S118934101 D against HD and S118934101 J against HJ.

Three more bases work the same way across two rows each: S118934103 across 5M51-12A650-GC and GD, S118934202 across AFA and AFB, and S118934203 across AGA and AGC.

The Focus, the C-Max and the 1.6

As a family, the SIM28 numbers in our table are on record from the petrol Ford Focus, most often with the 1.6, and from the C-Max on several rows. Row by row, the Focus is on record against every Ford number except 4M51-12A650-HB, which is on record from the C-Max.

The C-Max also appears alongside the Focus against 3M51-12A650-FF, 4M51-12A650-HC, 4M51-12A650-HE and 7M51-12A650-AFB.

For 3M51-12A650-FF, 4M51-12A650-HD, 5M51-12A650-GC and 5M51-12A650-GD, no engine size is on record often enough for us to state one. Against every other Ford number in the table, the 1.6 is.

Since car and engine agree across so much of the table, treat them as a check once the Ford number has made the match.

A SIM28 on our bench

Each SIM28 that reaches us is repaired in-house by our own engineers, in our UK workshop and on our own equipment. It is logged, inspected and tested electrically, then diagnosed against the fault you describe.

When diagnosis is finished we contact you with what we found and an estimate, and no chargeable work starts until you authorise it. The fault is then repaired at component level on the unit you sent, under a microscope with temperature-controlled rework equipment, and the repair is not complete until the unit passes final testing.

That repair carries our 24-month warranty.

Sending a SIM28 to us

A SIM28 comes to us by post, from anywhere in the UK, as every unit we repair does. Before you pack it, enter the label, last letter included, on our Repair Form: the Ford number with any code after it, and the Siemens number with its closing letter.

Tell us too whether it came from a Focus or a C-Max, the engine size, and the symptoms that made you suspect the ECU.

If the label names a different Siemens type, the Siemens SIM22 numbers we keep on a separate page may include it. Other Ford units are covered across the rest of our Ford engine ECU pages, and engine ECUs from outside the Ford range are listed from our main engine ECU repairs page.

The table below gives the Ford number in its first column and the Siemens number in its second.

Common part numbers associated with this type of unit