Audi RS4 ECU Failures After Software Update Stalls Car

Had a similar situation with my 2016 Audi RS5. The symptoms matched exactly, normal dash lights but no crank. After multiple ECU issues appeared during engine diagnostics, it turned out the main culprit was corroded battery terminals causing inconsistent power delivery to the ECU. The engine fault codes were misleading because poor battery connections can trigger multiple false readings. When the battery cables were cleaned and properly secured, the ECU issues cleared up completely. The engine surge problems I experienced beforehand also disappeared. This is a known weak point in these models. While not a severe mechanical issue, neglecting battery connection maintenance can cascade into apparent electronic failures. The ECU is particularly sensitive to voltage fluctuations. The fix requires: Removing battery terminals, Cleaning contact surfaces, Applying dielectric grease, Proper torque on terminal clamps, Clearing fault codes Best to have this checked before replacing more expensive components. Many shops jump straight to ECU replacement when seeing multiple fault codes, but starting with battery connections often resolves these symptoms.

Thanks for sharing your experience. This ECU failure diagnosis is quite similar to what I went through. My engine light came on right after I had the software update done too. Good to know the battery connection was the root cause in your case. Did you remember roughly how much you paid for the full fix? Also wondering if those engine fault codes ever came back or if you had any other electrical gremlins pop up since getting it sorted?

The check engine light and ECU issues were completely resolved after fixing those battery connections. Total repair cost was 155 Euro, much cheaper than replacing ECU components. The mechanic found significant corrosion at the terminals which was causing those misleading engine fault codes. Since having the cables properly cleaned and secured, all those electrical problems disappeared. No more engine control malfunction warnings or unusual ECU failures. It has been running perfectly with no warning lights returning. The battery connection fix was definitely the right call rather than jumping into expensive ECU replacements. These RS models are quite sensitive to voltage issues, and poor connections can trigger all sorts of false diagnostic codes. Regular battery terminal maintenance seems key to preventing these issues from recurring.

Just got back from the mechanic and wanted to update everyone. The fuel injection system and ECU were perfectly fine, turns out the previous software update triggered some ghost codes. My mechanic found heavy corrosion on the battery terminals, just like you mentioned. Total bill came to 180 Euro for cleaning connections, applying new dielectric grease, and clearing the check engine codes. Way better than the 2000 Euro+ quote I got for ECU replacement from another shop. Car starts perfectly now and all those unusual engine light warnings are gone. Really glad I checked here first before authorizing major repairs. Going to make battery terminal maintenance a regular thing from now on.