Removal and installation the ECM (Audi Q7-4L-D)

3.0L TDI-CR models

Note: After disabling the ECM, the adaptation values are erased, but the fault codes remain.

1. Before removing the ECM, read its identification data and coding. If the ECM is removed for replacement, connect a scan tool and perform the function "Replace engine control unit". If it is not possible to read the calibration data for the injectors from the old ECM, this data must be entered into the new ECM manually.

2. Turn off the ignition.

3. Remove the front rubber seal of the air intake chamber, unhook the right casing of the air intake chamber (see Section 19 of Chapter 1), lift it slightly and separate the ECM from under the cover (1 in illustration 4.31 Chapter 2) from the bracket without disconnecting the electrical wiring.

4. To restrict access to ECM connectors (1 in the illustration) secured to the protective casing (5) with a locking plate (2) and shear bolts (3 and 4).



Bolts (4) are screwed into the ECM with locking sealant. Bolts (3) are tightened without sealant.



5. Set the heat gun with the attachment to 600°C and the fan speed to maximum. Heat the locking plate in the area of one of the two bolts for 20-25 seconds (see illustration 5.5a), to melt the locking sealant, and then immediately unscrew the heated bolt with pliers (see illustration 5.5b).

Note: Avoid burning yourself on the bolts and casing.

6. Unscrew the second bolt in the same way, and then, without heating, unscrew the remaining two bolts. Separate the ECM from the protective plate and disconnect the electrical connectors.

7. Installation is carried out in reverse order. Before tightening the bolts with locking sealant, clean the threads of the holes. Use new shear bolts, tighten them until the head shears off. After installing the new ECM, activate it using a scan tool.

4.2L TDI-CR models

8. On 4.2L TDI-CR models there are two ECMs: the upper main (1 in illustration 35.30 Chapter 2) and the lower additional (2). The ECMs are connected via a separate CAN bus. The main ECM informs the additional ECM of the functions it should perform. Although both ECMs look the same, they cannot be interchanged, so they should be marked before removal

9. Removal/installation of the main ECM is carried out in the same way as on 3.0 L engines (see subsection above). The only difference when replacing the main ECM is that you only need to enter calibration data for injectors #1, 4, 6, 7. When replacing the additional ECM, you need to enter calibration data for the remaining injectors. The following describes the removal/installation of the additional ECM.

10. Turn off the ignition.

11. Remove the front rubber seal of the air intake chamber, unhook the right casing of the air intake chamber (see Section 19 of Chapter 1), lift it slightly and unscrew the bolts (see illustration 39.24 Chapter 2) front wall of the air intake chamber.

12. Pull the front wall together with the secondary ECM as far forward as possible. Just as when removing the main ECM, heat the shear bolts (arrows in the illustration), to melt the sealing compound and turn them out.

Note: The shear bolts securing the protective cover (3) are designed to restrict access to the connectors (4) of the additional ECM.

Remove the protective cover from the connectors.

13. Unscrew the bolt (arrow in the illustration) additional ECM holder fastenings, move the wiring aside, disconnect the ECM connectors and remove it together with the holder.



14. Release the ECM holder clips (see illustration) and remove it from the guide.



15. Installation is carried out in reverse order. Before tightening the bolts with locking sealant, clean the threads of the holes. Use new shear bolts, tighten them until the head shears off. After installing the new ECM, activate it using a scan tool.