XL7 Catalyst System Failing with Exhaust Leaks

I had a very similar situation with my 2008 Grand Vitara with the 2.7L engine about a year ago. As someone with moderate experience working on cars, I initially tried diagnosing the issue using a basic OBD scanner. The symptoms matched yours exactly, check engine light, noticeable exhaust noise, and catalyst-related codes. After monitoring increasing NOx emissions during diagnostics, my trusted workshop confirmed a crack in the exhaust system right before the NOx catalyst. They found the leak was allowing excess oxygen into the system, throwing off the readings and causing the check engine light. The total repair came to 265€, which included replacing the damaged section and ensuring proper sealing. After the fix, both the noise and check engine light issues were completely resolved, and the exhaust system returned to normal operation. For your XL7, knowing these details would help provide more specific guidance: Engine size and type, Current mileage, Whether the noise gets louder under acceleration, Location of the exhaust sound (front, middle, or rear of vehicle), Any performance changes or unusual smells These car diagnostics can be tricky since exhaust system problems often have similar symptoms but different root causes. Would you mind sharing those details?

Thanks for sharing those details. My XL7 just had its 15000km service last month when they also replaced the air filter. The exhaust noise definitely gets worse during acceleration and seems to come from underneath the middle section of the car. I have noticed slightly reduced fuel efficiency lately too. Based on your experience, I am wondering if I might have the same exhaust leak issue before the catalytic converter. The pricing at 265€ for your repair sounds reasonable compared to some quotes I have received. Did you notice any improvement in fuel consumption after fixing the exhaust leak in your case?

Thanks for the follow-up about your XL7. Yes, after fixing the exhaust leak on my Grand Vitara, I noticed a clear improvement in fuel efficiency, about 1.5-2L less consumption per 100km. The engine also ran smoother overall, especially during acceleration. The symptoms you describe with the noise location and acceleration behavior match my experience exactly. A compromised exhaust system often causes the engine to work harder, leading to that increased fuel consumption you mentioned. The recent air filter change rules out that common fuel efficiency culprit, pointing more strongly toward the exhaust leak theory. Car diagnostics showed that these exhaust system issues often start small but can worsen quickly. Getting it fixed promptly helped avoid more extensive automotive repair costs down the line. In my case, the leak had started affecting the oxygen sensor readings, which is what triggered the check engine light through the emissions system monitoring. The 265€ repair has proven cost-effective in my case, between the improved fuel efficiency and preventing potential catalyst damage, it was worth addressing quickly. Just make sure the repair shop pressure tests the entire exhaust system to catch any other developing issues while they are in there.

Since you provided those helpful details about your Grand Vitara repair, I will schedule an appointment with my local shop tomorrow. The similarities between our situations, especially the exhaust noise location and fuel efficiency problems, make me more confident about what to expect. Your mention of the pressure testing is particularly useful, I will specifically request that to ensure they catch any other potential issues. The fact that fixing your exhaust leak improved both the fuel consumption and engine performance gives me hope this repair will resolve my problems too. From what you describe about NOx emissions and catalyst issues, taking care of this soon seems like the smart move to prevent more expensive repairs. That 265€ price point helps me better evaluate the quotes I have received. Good to know the repair made such a noticeable difference in your fuel efficiency too, that kind of improvement would definitely help offset the repair cost. I will update once I get the car diagnosed and repaired. Thanks for sharing your experience with such helpful details about the emissions system repair process.