Ford Siemens SIM 29 Engine ECU Repairs

Type: Siemens Engine Management
Fits: Ford
Engines:
Year:
Fuel: Petrol
Ref: ECUT26175

Note: This ECU may also fit other models.

Do not work out one number on a Siemens SIM29 label from the other. On the pairings on record for the Ford numbers in our table, the Siemens letter sometimes runs one step on from the last letter of the Ford number and sometimes repeats it, so a letter worked out rather than copied can easily point at the wrong row. Copy both numbers exactly as printed, and let the Ford number make the match.

Where the Siemens letter runs on, and where it repeats

Three Ford numbers in our table end in HE, HF and HG. On record, 5M51-12A650-HE goes with S118944001 F, HF with S118944001 G and HG with S118944001 H, so on each the Siemens letter sits one step further along the alphabet than the Ford number’s last letter.

The remaining four pairings on record behave differently. 5U71-12A650-DA goes with S118944002 A, 6M51-12A650-AAB with S118944012 B, 7M51-12A650-KA with S118944005 A and 7M51-12A650-KB with S118944005 B. On these, the Siemens letter repeats the last letter of the Ford number.

Neither pattern covers every pairing on record. Copy the letter from the label: worked out from the other number, it would go wrong on three of the seven pairings on record or on four, depending on which pattern you assumed.

Two Siemens numbers shared across five rows

S118944001 is on record with three Ford numbers in our table, HE, HF and HG, and S118944005 with two, KA and KB. For those five, the Siemens number without its letter narrows the choice but cannot settle it.

The Ford number can, because it differs on every row. That makes it the safer match, with the Siemens letter from your label as a check against the pairings above.

Where our table prints a Siemens number with no letter, expect a Siemens number with a letter on your label; on those rows the Ford number makes the match on its own. Against 5M5112A650HE our table prints S118944001 F, and against 6M5112A650AAB it prints S118944012 B, both in line with the pairings on record.

Copying the Ford number and the code after it

Our table prints each Ford number without its hyphens, so 5M51-12A650-HE appears as 5M5112A650HE 8AZE. The short code after the number is printed on each row of our table, and we want it from your label too, character for character.

Several of these codes are also on record beyond our table: 8AZE beside HE, 8AZG beside HG and 7DHB beside KB each appear on labels in several independent sources. We ask for the whole label, code included.

One Ford number needs extra care. 6M51-12A650-AAB ends in three letters rather than two, so copy all three instead of stopping at AA.

The petrol Focus, most often with the 1.6

As a family, the SIM29 numbers in our table are on record from the petrol Ford Focus, with the Focus C-Max alongside it, and most often with the 1.6.

Row by row, the Focus is on record against 5M51-12A650-HE, HF and HG, 6M51-12A650-AAB, and 7M51-12A650-KA and KB. The 1.6 is on record against all of those except KA. For 5U71-12A650-DA, no car or engine size is on record often enough for us to state one.

A petrol Focus 1.6 is shared by almost every row here, so the label, not the car, places your unit on a row.

What happens to a SIM29 once it reaches us

Every SIM29 we receive is logged, visually inspected and tested electrically, then taken through diagnostics aimed at the fault you describe. The work is done in-house by our own engineers, in our UK workshop and on our own equipment.

After diagnosis, we contact you with the outcome and an estimate, and no chargeable work begins 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 complete only once the unit passes final testing.

A 24-month warranty applies to the repair we carry out.

Getting a SIM29 to our workshop

A SIM29 reaches us by post, from wherever in the UK it happens to be. Before it leaves you, fill in our Repair Form with both numbers: the Ford number with the code after it, and the Siemens number with its letter.

Tell us which engine the car has and what it was doing that pointed you to the engine ECU.

If the label names another Siemens type, other Siemens engine ECUs from the Focus are listed on our SIM28 page. For a different Ford engine ECU, try our Ford page, and engine ECUs made for other car brands are on our main repairs page.

In the table below, the left-hand column holds the Ford number and the next column the Siemens number.

Common part numbers associated with this type of unit