VW / Audi / Seat / Skoda (VAG) Bosch ML5.9 Engine ECU Repairs

Type: Bosch Engine Management
Fits: VAG – Audi / Seat / Skoda / Volkswagen (VW)
Fuel: Petrol
Ref: ECUT199195

Note: This ECU may also fit other models.

This page is for one Bosch ML5.9 engine ECU. Its Bosch number is 0 261 203 266, the vehicle-manufacturer number recorded with it is 037 906 024 D, and the car it is recorded on is the Volkswagen Golf 2.0. If the unit off your car and the car itself agree on all three points, you are in the right place, and what follows is about confirming the match properly and getting the unit repaired.

The cars and engine size named here are the ones independent records agree on. Details that appear in a single listing have been left out, so this page says less than some listings do, and nothing it cannot support.

The two numbers that identify this ML5.9

Two numbers do the identifying. 0 261 203 266 is Bosch’s own reference for the unit, and 037 906 024 D is the Volkswagen Group part number it carries. Five independent sellers list the two together, so a unit carrying both is the one this page describes.

Each number is written in more than one way. Listings give the Bosch reference with its spaces and without them, as 0261203266, and the Volkswagen number is also run together as 037906024D. They are the same numbers in different dress, and searching on both forms finds the same unit.

Independent sources also attach the ML5.9 name to this reference, which is why it sits on this page. The name covers a family of Bosch units rather than one part, though, so it narrows the search without closing it. The two numbers close it.

Read both from the label on the case, not from an invoice or a previous garage’s notes, and take every character. Paperwork gets copied and recopied; the label is the one record that travelled with the unit.

Which Volkswagen this ML5.9 is recorded on

The record points clearly at the Golf. Eleven independent sources name the Golf against 0 261 203 266, ten give the engine as a 2.0, and seven name the GTI. A Golf 2.0, and the GTI above all, is the car this unit is most consistently documented on.

The Vento and the Passat are recorded against the same reference too, each by two independent sources. That is enough to name them here and not enough to build on. If your unit came out of either, match the label first and treat the car as background.

The Fits: line at the top of the page names the VAG group as a whole, as it does across this part-number library. The cars in this section are narrower by design: they are the ones the independent records place against this single reference, and no others are claimed for it.

If your Volkswagen turns out to carry a different unit, look for it among Volkswagen engine ECUs, family by family.

When the label does not match

A unit whose numbers differ from both of those above is a different part, even if it came out of a Golf 2.0 and is described as an ML5.9. That does not rule it out of repair. It means the unit belongs on another page.

For a unit off another make, or a reference you cannot place at all, work down from our engine ECU repair catalogue, which starts from the make of car.

If one number is legible and the other is not, send us the one you can read along with the car the unit came from, and we will tell you whether it matches this page.

What happens to an ML5.9 in our workshop

The unit comes to us by post from anywhere in the UK. On arrival it is logged and inspected, tested electrically, and then taken through diagnostics aimed at the fault it came in with, so we are working from what the unit actually does on the bench rather than from the symptom described.

Repairs are made at component level by our own engineers, in our own UK workshop, under a microscope and with temperature-controlled rework equipment. The engineer finds the part on the board that has failed and puts it right; your unit is repaired, not exchanged for one from another car.

When the diagnosis is done we contact you with the findings, and no repair work begins until you have agreed to it. Nothing is sent back until it has passed final testing, and the repair is covered by a 24-month warranty.

To get started, raise a repair enquiry with both numbers and tell us the car the unit came from. We check what you send against this page before anything goes in the post.

The table below sets out the Bosch and Volkswagen numbers as we list them.

Common part numbers associated with this type of unit