VW / Audi / Seat / Skoda (VAG) Magneti Marelli 4HV Engine ECU Repairs

Type: Magneti Marelli
Fits: VAG – Audi / Seat / Skoda / Volkswagen (VW)
Fuel: Petrol
Ref: ECUT250225

Note: This ECU may also fit other models.

Six Magneti Marelli IAW 4HV engine ECUs are covered on this page, and on the part records we have checked they are close relations. All six are petrol units in Volkswagens or Seats, and every one with an engine size on record sits behind a 1.4.

One of them breaks rank. The IAW 4HV.AF is recorded in both a Seat Ibiza and a VW Polo, while each of the other five stays inside a single model, so the AF is the fixed point this page works outward from.

What the six IAW 4HV units have in common

Every unit here is a Magneti Marelli petrol engine ECU, and the cars on record for them come from two makes only: Volkswagen and Seat. Three models account for all of them: the VW Polo, the VW Golf and the Seat Ibiza.

Engine size does little to sort them. Five of the six are recorded behind a 1.4 petrol engine, and none is recorded behind any other size, so knowing that a unit came off a 1.4 leaves every candidate in play.

What separates them is the variant, the part of the Marelli reference after the dot: AD, AF, AP, AS, BD or H. IAW 4HV is common to all six, so it is the variant you need from the label. Each unit also carries a Volkswagen part number, and on all six it begins 03C 906 024.

If the case shows a Marelli reference that is not one of these six, it belongs to a different engine ECU, and our general engine ECU repair service is where to look for it.

The IAW 4HV.AF: one unit, two makes

The AF is the only 4HV on this page recorded under both makes. The part records place it in the Seat Ibiza and the VW Polo, describe it as a unit for a 1.4 16V engine, and pair it with the Volkswagen number 03C 906 024 AF.

An AF taken from a Polo and an AF taken from an Ibiza are the same unit. The make of the donor car adds nothing to the identification, and we repair it the same way whichever car it came out of.

That reach has a knock-on effect. Because the AF appears in both makes, it is a candidate whether a unit came from a Polo or an Ibiza, and it is the only 4HV on this page that is.

For a Seat unit whose label reads something other than IAW 4HV, our Seat engine ECU pages are the next place to look.

The Polo and Ibiza units beside the AF

Three other 4HV units share a model with the AF. In the Polo it sits alongside the IAW 4HV.AD and the IAW 4HV.AP; in the Ibiza, alongside the IAW 4HV.H.

That leaves a Polo with three possible 4HV units and an Ibiza with two. The model and the engine size cannot narrow either car further, so for both the variant on the label settles it.

The AD is a VW Polo unit, recorded behind a 1.4 16V engine with the engine code BUD, and carries the Volkswagen number 03C 906 024 AD. Of the three Polo units, it is the only one we give an engine code for; use BUD to confirm an AD label, not to choose between the three.

The AP is recorded in the VW Polo, and the part records settle nothing further about it. Identify it by the IAW 4HV.AP marking on the case.

The H is a Seat Ibiza unit, recorded behind a 1.4 engine, with the Volkswagen number 03C 906 024 H. It and the AF are the two 4HV units on this page found in the Ibiza.

The Golf pair: IAW 4HV.AS and IAW 4HV.BD

The AF is not recorded in a Golf, and nor are the AD, AP or H. The Golf has a pair of its own, the IAW 4HV.AS and the IAW 4HV.BD, both recorded behind a 1.4 engine.

The BD comes with more detail. The records describe it as a 1.4 16V from the CGG engine family, and its Volkswagen number is 03C 906 024 BD.

The AS carries the Volkswagen number 03C 906 024 AS. The records disagree on its engine code, so we give none. Between the two, a CGG engine points towards the BD; without that detail, a Golf unit comes down to the variant on its label, as the Polo and Ibiza units do.

For a Volkswagen engine ECU from another family, see the Volkswagen engine ECU types we work on.

How we repair an IAW 4HV

A 4HV reaches us as a mail-in repair from anywhere in the UK. On arrival we note what its label says, look it over for physical damage and put it on electrical test, then work towards the fault you described.

The repair is made at component level by our own engineers, in our UK workshop. The fault is traced to the part responsible on the circuit board and corrected there, under a microscope and with temperature-controlled rework equipment, rather than the whole ECU being exchanged.

You hear what we found before any chargeable work begins, and the repair goes ahead only when you tell us to. The unit is tested once more at the end, and the repair carries a 24-month warranty.

Before anything is posted, pass us what the case says through the Repair Form. The variant after the dot matters most, and the car the unit came from helps us confirm it.

All six IAW 4HV units are listed with their Volkswagen numbers in the table that closes this page.

Common part numbers associated with this type of unit