RS5 - Secondary Air Pump Replacement (No Engine Start)

A5/S5/RS5
#1

Hi all,

Working with RedMist on this issue, but wanted to document here for others.

After a VCDS scan, I had a code for the Secondary Air Pump and decided to replace both at the same time. After installing both pumps, I now have no communication to the ECU and the car won’t start. I have full electronics, except the engine won’t even attempt to turnover.

I have checked all fuses, and replaced all of the relays related to the ECU, but still no luck. During the repair, I did have to remove the ground connection in the passenger side wheel well, but I have since checked that to make sure it was secure, but there was no change.

Currently, I have a code for the ABS Valve Supply Voltage (01200). Not sure that this is related, but just about the only thing I can see in the scan as I have no OBD function with no ECU communication.

Current dash lights: Stabilization control fault, TPMS, Sport diff Fault, ABS and Brake light, Parking brake Malfunction (but oddly enough this is still working as expected).

Has anyone had similar issues? Any insight here would be greatly appreciated as I’ve hit a dead-end.

#2

First thing I would have said was that ground point you mentioned under the right wheel well liner. Did you just pull the front wheels and front wheel liners or did you pull the front bumper too? Did you disconnect anything from the power panel under the windshield cowl cover?

#3

Only the wheels and liners. I didn’t pull anything from the power panel. I dug around and it seemed that other Audi models had similar issues/lights that were resolved by replacing the main relay, which was not the case for me.

#4

Double check that Ground connection, if I remember right there should be two ground connections that go to this, maybe you only connected one of them??

#5

Double checked the ground. Cleaned the connections really well but no change. I’ve run out of ideas so likely going to have it towed to my mechanic.

#6

WIth vag com. Check off the list of modules you can connect to. If the modules all located under the hood are off line. There might have been a damaged wire. If you can’t communicate to the ECU… Check power to the ECU with a volt meter… It might be as simple as a power line/ground wire trace back