VW / Audi / Seat / Skoda (VAG) Bosch EDC16U1 Engine ECU Repairs

Type: Bosch
Fits: VAG – Audi / Seat / Skoda / Volkswagen (VW)
Fuel: Diesel
Ref: ECUT334295

Note: This ECU may also fit other models.

The boost pressure sensor, the accelerator pedal and most of the other sensors around one of these engines do not generate their own electricity. Each is fed a regulated five-volt supply, and that supply is produced inside the engine ECU and sent out to them. It is a diesel engine ECU. We take these in, test them completely, and rebuild them.

Why one fault looks like several

When that supply fails inside the unit, nothing is wrong with the sensors themselves. They are simply no longer being given anything sensible to work with, so they all report something impossible at the same moment. A scan taken at that point reads like half the engine failed at once — several unrelated readings wrong together, in a combination no engine could actually produce.

That is the one fault picture that looks worst and means fewest separate things. Read literally, it points at several different components and invites each to be changed in turn. Changing them achieves nothing, because there was never anything wrong with any of them, and the next scan comes back saying the same thing. Weeks go by, parts go on, and the picture does not move.

What it does on the road

The supply rarely fails cleanly, and the way it lets go is what makes this so hard to catch. The vehicle is fine cold and fine for the first part of a journey. It is at the end of a long run that it stops, and then it will not restart. Leave it standing until everything has cooled and it starts perfectly, so the fault has usually cleared itself long before the vehicle reaches a ramp and anybody looks at it. At the milder end it is intermittent rather than absolute, and the ignition has to be cycled on and off several times before the engine will catch.

At the harder end there is no engine management light at all and no communication with the ECU. There is nothing to read and no code to chase, which is where a diagnostic session on the vehicle runs out of road. Nothing can be interrogated because nothing is answering. That is why a unit in this state is settled off the vehicle, on test equipment that supplies it and watches what it does, rather than on the car.

An internal fault on a sound unit

None of this is damage to the vehicle. It is an internal fault on a unit that is otherwise sound, and it sits inside the ECU where it can be worked on. What testing settles is whether a particular unit is recoverable, and that is a question about the unit in front of us: we will not promise a repair before we have seen one, and we will not talk anyone out of having one looked at either. We do not clone units, bypass immobilisers or remap them.

Vans and cars on the same ECU

The heading on this page reads like a car page, and a good part of the numbers underneath it are not cars at all. The T5 Transporter runs this unit in both 1.9 TDI and 2.5 TDI form, and the Caravelle, the Multivan and the California share it; the 2.5 is Bosch 0281011568, VAG 070 906 016 AJ. The Caddy is here too, on 2.0 SDI, as Bosch 0281014069 with VAG 03G 906 016 LF. So is the Touareg. A van owner or a fleet chasing this fault has no obvious way of telling this page is about their vehicle, so it is worth saying plainly: it is.

The table also spans two different kinds of diesel. The Caddy and the Golf 2.0 SDI are naturally aspirated, with no turbocharger to manage, while everything with TDI after it is turbocharged. Among the cars, the unit covers the Golf in 1.9 TDI and 2.0 TDI, the Touran, and the Audi A3 in the same two engines. Nothing here covers the EDC16U31, which has a page of its own, and units of other types are grouped by make among the Volkswagen engine ECUs we cover.

How a unit is handled here

A unit that arrives here is given a job number of its own, looked over for physical damage, and then powered up and tested before anybody offers a view on it. What the test found comes back to you with what the repair involves, and nothing chargeable begins until you have agreed to it. The work is done in our own UK workshop by our own engineers, at component level on the board that came out of your vehicle. Afterwards it is tested again, and that second test is the last gate before it is packed. There is a 24-month warranty on the repair carried out.

What helps most is the order things happened in. A long run, then a stop, then nothing at all until it had cooled down — that sequence points at the supply before the unit is even opened, and it is the detail most people leave out. Put that in a note on the Repair Form, and the ECU can be posted in from anywhere in the UK.

Common part numbers associated with this type of unit