Audi A6 EGR Problems Cause Multiple Engine Issues

I had almost identical issues with my 2011 A4 from about 2 years older than yours with similar mileage. With some experience working on performance cars, I recognized these symptoms immediately. The check engine light, power loss, and rough idle perfectly match what I experienced. The vacuum leak symptoms and vehicle emissions problems were a clear indication of a faulty EGR valve in my case. The hissing sound during acceleration was particularly concerning. My repair involved: Complete EGR valve replacement, Cleaning of the EGR recirculation passages, New gaskets and seals, System diagnostics and reset Total cost was 355 Euro for parts and labor. The repair took about 4 hours at my regular workshop. After the fix, all symptoms disappeared and fuel economy returned to normal. To provide more specific advice about your case, could you share: Build year of your A6? Engine type and size? Any modifications to the exhaust or engine management? Did you notice any catalytic converter related codes during the scan? These issues often get worse if left unaddressed, so I would recommend having it checked soon to prevent additional damage to related components.

Thanks for sharing your experience. After reading through the symptoms you described, Im now at 169792 KM and recently completed my routine service. The EGR valve issues you mentioned align with what Im experiencing. My mechanic confirmed the vehicle emissions problems are linked to EGR system failure, affecting overall engine performance. The repair estimate I received was 420 Euro, including a new EGR valve, gaskets, and cleaning of the recirculation system. They also recommended checking the catalytic converter as its showing some concerning readings. Before proceeding with repairs, did your workshop perform any specific diagnostic tests beyond the standard OBD scan?

In my case with the A4, the workshop did perform additional diagnostic tests before replacing the EGR valve. They specifically checked the exhaust backpressure which can indicate if the catalytic converter is contributing to the rough idle and performance issues. The vacuum leak testing was particularly important as it revealed the full extent of the EGR system deterioration. My repair costs were lower because we caught it before it impacted the catalytic converter. The diagnostic testing added about 85 Euro to my total bill but saved money in the long run by identifying all affected components. A complete diagnostic test should include: Smoke test for vacuum leaks, Exhaust backpressure measurement, EGR flow rate testing, Catalytic converter efficiency check If your readings suggest catalytic converter issues, addressing both problems simultaneously might be more cost-effective. In diesel engines especially, a faulty EGR valve can eventually damage the catalytic converter due to improper exhaust flow. The price quote you received seems reasonable considering current parts costs. Just ensure they clean all EGR passages thoroughly during the repair to prevent future issues.

Thanks for the thorough diagnostic information. My 2013 A6 is stock with no modifications. The scan showed P0401 and P0402 codes related to EGR flow. Your repair experience matches exactly what my mechanic suggested. They want to run the complete vacuum leak test and emissions test sequence you mentioned before proceeding. The 420 Euro estimate includes full diagnostics with the smoke test and catalytic converter inspection. Given the check engine light and performance issues keep getting worse, I scheduled the repair for next week. The hissing sound during acceleration is definitely concerning, and I dont want to risk damaging other components by waiting too long. Did your fuel economy and performance return to normal immediately after the repair, or did it take some time for the system to adjust? Also wondering if the recirculation system cleaning made a noticeable difference in how the engine runs. I appreciate the detailed breakdown of your repair process. It helps confirm Im on the right track with addressing these issues before they cause more extensive damage.