Cayenne Diesel Woes: EGR Valve or Something Worse?

Hey there! I have some experience with cars and had a similar issue with my 2003 VW Touareg Diesel (pretty close to your Cayenne since they share platforms). Had exactly those symptoms you're describing, rough running, power loss, and that annoying check engine light. Turned out it was indeed the EGR valve that was stuck open. Took it to my regular workshop, and they confirmed it after diagnosis. Cost me 355€ for the replacement and labor, but it's been running like a charm since then. What's your mileage and have you checked for any fault codes? Also, when was the last time you had any EGR-related maintenance done? Let me know, might help pinpoint if we're dealing with the same issue. P.S. My had the same problem on his Porsche Macan a while back, so it seems to be a common issue with these VAG diesels.

Thanks for sharing your experience! My mileage is at 55012 KM, and I had my latest service about 3 months ago. Haven't done any EGR maintenance specifically though. That's really helpful to know about your Touareg, it's good to hear it was a straightforward fix. I've been worried it might be something more serious. Did you notice any improvement in fuel consumption after the repair? I might take it to the dealership this week to get those codes checked. The symptoms you described are spot on with what I'm experiencing.

Hey again! Yeah, after fixing the EGR valve on my Touareg, I definitely noticed some improvements in fuel consumption, probably getting about 2-3 mpg better now. The engine also feels much smoother, and that annoying diesel smell is completely gone. Just a heads up though, since your Cayenne has relatively low mileage (mine was at 120,000 km when it happened), you might want to also check for carbon buildup in the intake manifold. When they fixed my EGR, they found quite a bit of carbon deposits that needed cleaning. Cost me an extra 150€, but it was worth it for the peace of mind. Quick tip: if you're heading to the dealership, ask them to check the EGR cooler too while they're at it. These VW/Porsche diesels sometimes have issues with both components. Mine was fine, but better safe than sorry, right? Keep us posted on what they find! Always interested to hear how these shared platform cars behave.

Thanks so much for all these details! Really appreciate the tip about checking the carbon buildup and EGR cooler, that's not something I would've thought to ask about. I've actually just booked an appointment at the dealership for tomorrow morning. The extra fuel consumption info is super helpful too, I've definitely noticed mine's been drinking more diesel lately, so hopefully fixing the EGR will sort that out. I'll keep you updated on what they find after the diagnostic. You've really put my mind at ease about this whole situation, especially knowing it was a manageable fix on your Touareg. Thanks again for taking the time to help out!