VW / Audi / Seat / Skoda (VAG) Bosch EDC15P Engine ECU Repairs

Type: Bosch
Fits: VAG – Audi / Seat / Skoda / Volkswagen (VW)
Fuel: Diesel
Ref: ECUT226225

Note: This ECU may also fit other models.

On the 1.9 TDI PD, a fault logged against one cylinder’s injector circuit is the usual reason someone ends up holding the engine ECU. Most of the time the ECU is not what has failed; it is reporting a circuit that has. Sometimes the failure is inside the ECU itself. It is a diesel engine ECU, and a full test and rebuild is work we do in-house.

Whoever read the codes will have seen a cylinder named and an injector circuit named with it. That is a statement of where the fault is being sensed, not of which part has failed. The engine ECU watches what happens on that circuit every time it fires the injector, and it logs the cylinder when what it reads is wrong. Everything on the circuit is a candidate at that point, the ECU included.

On these engines it is usually not the ECU. The injector itself is the first candidate, with its hold-down and the torque on it close behind, then the injector loom, then the supply and the earth at that one injector. A poor connection anywhere in that chain leaves the ECU reading a voltage drop it did not expect, so the code that follows is an accurate report of a real fault at a point the ECU cannot see. Diesel injectors are not work we take on.

The faults independent repairers list against these units read differently on the car. An internal control-module fault, logged against the ECU’s own memory. An engine that will not run at all. A unit that has stopped communicating. No control of the fuel-pump relay. Alongside those, the physical failures: dry joints on the board, water that has got inside, and starting that works one morning and not the next. Those are failures of the board itself, and they are not the same picture as one cylinder’s circuit playing up.

Both sets of symptoms can produce the same reading in the car, which is what makes this hard to settle on a driveway. In the vehicle, the ECU, the loom and the injectors are one circuit, and a code reader can only report what that circuit did. Off the car, the ECU stands alone: it is powered and tested on the bench with no injector and no loom in front of it, so what the board does is separated from what the car does. That is the test that answers the question, and it is the one no code reader plugged into the car can do.

A unit that tests clean is worth knowing about as well. It takes the ECU off the list and sends the work back to the circuit, which is where it was probably always going to end up on a cylinder-specific fault.

Two units are on this page and both came off the same engine, the 115 hp 1.9 TDI PD with the AJM engine code. Bosch 0281010091 is the Golf Mk4 and Bora unit; Bosch 0281010176 is the Passat B5 one. Each is listed below beside the VAG number it carries. Both are Volkswagen cars: what we record here are the numbers we have logged, not everywhere the unit was fitted.

If what you are holding is an EDC15P+ rather than an EDC15P, the EDC15P+ units are listed separately.

The sequence here does not vary. A unit is booked onto a job when it arrives, inspected, and then tested electrically. We come back to you with what the test found and what the repair involves, and nothing chargeable begins until you have given the go-ahead. The repair is made to the board rather than by swapping the unit: the failed part is identified and renewed with temperature-controlled soldering equipment, on our own bench, by the engineers who tested it, and nothing is sent out to anyone else at any point. The last thing a repaired unit does here is go back on test, and it does not leave until it passes. Every repair carries a 24-month warranty.

If the car is a Volkswagen but the ECU is a different unit altogether, look through what we list under Volkswagen. The service is postal in both directions, anywhere in the UK.

If the injector, its hold-down and the wiring to it have all been checked and the cylinder is still down, the ECU is what is left to prove. Set out what the engine is doing, with the numbers off the unit, on our Repair Form.

Common part numbers associated with this type of unit