Bosch DME M 3.3 Engine ECU Repairs

Type: Bosch Engine Management
Fits: BMW 316i / 318i / 325i / 525i / 530i / 540i / 730i / 740i / 840i
Engines: E31 / E32 / E34 / E38
Year: 1993 – 1995
Ref: ECUT314195

Note: This ECU may also fit other models.

A single digit separates the name at the top of this page from the name recorded for one of the two units it covers. Bosch 0 261 200 404 is listed as a Motronic M3.3, while 0 261 200 413 is listed as an M3.3.1. The two units also belong to different engines: the first to BMW’s M60 V8, the second to the M50 2.5 straight-six with VANOS.

What the extra .1 on the case tells you

We file both references under M3.3. In the listings we checked, the 413 unit is recorded as M3.3.1, so a case carrying that name has come to the right page, and the extra digit has already pointed you towards the six-cylinder row.

The 404 unit is recorded under the plain M3.3 name. The name, the engine and the part number usually point the same way, and the label settles any doubt.

Eight cylinders or six: matching the car to a row

Count the cylinders and you have the row. A V8 points to 0 261 200 404, recorded in the 540i, 740i, 840i, 530i and 730i. At chassis level, the 530i and 540i are E34s, the 730i and 740i are E32 or E38, and the 840i is an E31.

A six-cylinder points to 0 261 200 413, recorded in the E36 325i and the E34 525i with the VANOS M50 2.5.

The E34 appears on both rows, so the chassis code on its own settles nothing: a 525i and a 540i share it, but not an engine or an engine ECU. Go by the badge and the engine, then let the label confirm.

When the BMW number on a 404 label is not 1744606

Our table pairs 0 261 200 404 with BMW number 1744606, and that pairing holds across nine of the listings we checked. A few listings print a different BMW number beside 404, so the one on your label may not match ours.

That is not a sign the unit belongs elsewhere or has been mislabelled. Copy the BMW number exactly as it is printed and send it with the Bosch number; we identify the unit from your label, not from our table.

The six-cylinder unit is more settled: 0 261 200 413 is recorded with BMW number 1703563 in eleven listings, matching the table.

Where the print has faded or part of the label is missing, send what you can read and say which part is gone. We will not fill the gap from the car’s details.

What we do with an M3.3 once it arrives

Each unit is logged against the details you sent, checked by eye and electrically tested, then taken through diagnostics chosen for the fault you described. It is handled throughout by our own engineers, in our own UK workshop, on our own equipment.

Once the cause is found, we contact you with what we found and a quote, and no chargeable work begins without your go-ahead.

The repair is made at component level. Failed parts on the circuit board are traced and renewed under a microscope using temperature-controlled rework equipment, and the unit is not finished until it passes final testing. The specific repair carried out is covered by our 24-month warranty.

The DME that returns to you is the one you posted, with the same Bosch and BMW numbers on its case.

Sending your M3.3 or M3.3.1 by post

We are a mail-in workshop and take units from anywhere in the UK. Before the DME is packed, note the name on its case, the Bosch number, the BMW number as printed, the model, and whether the engine is a V8 or a six, then set it all down on the Repair Form. A line or two on how the car has been running helps us too.

If the case names a designation other than M3.3 or M3.3.1, look for that name among our BMW pages. For an engine ECU from a car of another make, go to our engine ECU front page.

Both Bosch references, with the BMW number we list beside each, are set out in the table below.

Common part numbers associated with this type of unit