VW / Audi / Seat / Skoda (VAG) Bosch EDC MSA 15.5 Engine ECU Repairs

Type: Bosch
Fits: VAG – Audi / Seat / Skoda / Volkswagen (VW)
Fuel: Diesel
Ref: ECUT333225

Note: This ECU may also fit other models.

A Bosch MSA 15.5 carries two part numbers. Both are correct, and they answer different questions — which is why the list further down this page has two columns rather than one. It is a diesel engine ECU, and we test and rebuild these units.

The VAG number is the one most people already have. It begins 028 906 021 on the four-cylinder 1.9 diesels and 074 906 021 on the five-cylinder 2.5, with a letter suffix on the end. It is the number that travels with the paperwork — invoices, parts catalogues, an enquiry to a garage — so it is the one a VAG owner tends to quote. What it tells you is what the part was supplied as, and for which engine.

The Bosch number is the other half. It begins 0281 on every unit on this list, and it belongs to the hardware rather than to the car. It is what the unit is on the bench, and it is what a repairer works from once the case is open.

Which of the two you have usually depends on where you are standing. An owner with the car and the paperwork behind it will have the VAG number. A garage or a trade buyer with the unit in a box and no vehicle beside it will have the Bosch number. Both are workable starting points.

The two do not map one to one, and the list itself shows it. 028 906 021 AT appears against two Bosch numbers, 0281001368 and 0281001369. 028 906 021 BF appears more than once too, against 0281001421 and 0281001422 among them. A VAG number on its own therefore does not settle what is inside the case, and a Bosch number on its own does not say which vehicle it came out of. Each column answers half of it; between them they answer the whole.

Three of the pairings on the list are independently confirmed. 0281001306 goes with 074 906 021 A, on a VW Transporter T4 2.5 TDI; the same holds for 0281001368 with 028 906 021 AT on a VW Passat 1.9 TDI, and for 0281001421 with 028 906 021 BF on a VW Golf III 1.9 TDI. The prefix follows the engine in each: 074 on the five-cylinder 2.5, 028 on the four-cylinder 1.9. Read as pairs, they tell you both things at once — what the hardware is, and what it went into.

That is what the two columns are for. If the Bosch number is the one you have, read down the first; if it is the VAG number, read down the second. Either way the row you land on carries both halves, and it is a unit we have had in. A number written down on a job card is enough to find the row; the unit does not have to be in front of you.

The list itself is a record of what has come through the workshop rather than a complete catalogue of every number this ECU was built under. That is the plain meaning of the note near the top of this page: a number that does not appear on it has not been ruled out, it has simply not been logged here.

Most arrive here after a non-start, or after a van that will not pull.

Whichever number you arrive with, the work runs the same way. The unit is recorded on arrival, inspected and electrically tested, and you are told what that found and what putting it right would involve, with the price on application; no chargeable work happens without your agreement. Repairs are carried out at component level on your own board — the failure found on the board itself and the component replaced with fine-tipped rework tools, by our own engineers in our own UK workshop, with nothing sent out. A repair is not finished here until it has passed final testing, and it carries our 24-month warranty.

Other engine ECUs we handle for the same marque are in our Volkswagen coverage. We work by post, wherever in the UK you are.

Quote whichever number you have — both if the unit came with both, one if that is all there is. The unit itself fills in the rest once it is on the bench. Put it on the Repair Form, or read it out on 0208 853 5000.

Common part numbers associated with this type of unit