Q5 Engine Troubles Point to Faulty EGR Valve

I had a similar issue with my 2015 A4 last year and can relate to these symptoms, especially the rough idle and increased fuel consumption. Having some experience with vehicle emissions systems, I recognized these classic signs of EGR valve problems. The symptoms you describe match my experience perfectly. The recirculation system malfunction caused my engine to run poorly, particularly at idle. After the emissions test failed, I took it to my regular workshop where they confirmed a jammed EGR valve was the culprit. The repair, including parts and labor, cost me 355 Euro. The repair resolved all issues: smooth idle returned, normal power delivery restored, exhaust smoke disappeared, check engine light cleared, fuel consumption normalized. To provide more specific advice for your automotive repair situation, could you share: Current mileage? Service history of EGR system? Any recent engine work? Specific error codes from the check engine light? When symptoms first appeared? This information would help determine if your situation mirrors mine and whether other components might need inspection.

Thanks for the responses. Just had my mechanic look at it, turns out the diagnosis pointed to a clogged catalytic converter, not the EGR valve. The emissions test readings were way off. They found the cat was completely blocked, restricting exhaust flow. This explains the drop in power and smoke issues. For reference: Last service was at 162000 KM with a full inspection. Currently at 164013 KM. Looks like I jumped to conclusions about the recirculation system. Getting the catalytic converter replaced next week. Mechanic quoted 1200 Euro for parts and labor. At least this should solve all the symptoms at once.

Thanks for the update regarding your catalytic converter diagnosis. This actually makes perfect sense, as clogged catalytic converters and EGR valve issues can present very similar symptoms in diesel engines. During my repair experience, I initially thought my symptoms pointed to the EGR valve too, but a thorough check engine diagnostic revealed multiple issues. Your quoted price of 1200 Euro is fairly standard for a complete catalytic converter replacement. When I had mine replaced, the cost was similar, and it resolved comparable symptoms: power loss, check engine warnings, excessive exhaust smoke, poor fuel economy. One recommendation based on my experience: have them check the EGR valve and oxygen sensors while they are working on the exhaust system. These components often get stressed when the catalytic converter fails, as the vehicle emissions system tries to compensate for the blockage. The timeframe between your last service and current issues suggests this might have developed fairly quickly. After my repair, I started monitoring exhaust back pressure more regularly to catch any future problems early. Keep us posted on how the repair works out. Based on your mileage, a new catalytic converter should give you many years of trouble-free operation.

Thanks for the helpful feedback. Quick update after getting the catalytic converter replaced, all the symptoms have completely cleared up. The automotive repair shop was right on target with their diagnosis. My engine is running smooth again with no power loss or smoke. The total cost came in exactly as quoted at 1200 Euro. They did check the EGR valve during the repair as suggested and confirmed it was working properly. No vacuum leaks or other issues were found in the diesel engine components. For anyone facing similar symptoms, while EGR valve problems were my first suspicion, it really showed the importance of getting a proper diagnosis rather than assuming. The exhaust gas recirculation system was fine, and the real culprit was the clogged cat. The car feels like new again. Thanks for helping me understand these issues better and guiding me toward the right fix.