G6 Exhaust Leak and NOx Error

Exhaust leak AND NOx issues? Sounds familiar! I had a similar problem on my G6. Started with the check engine light and a vague 'emissions' error. I'm betting that the leak is upstream of the catalyst. That messes with the whole system, causing the NOx readings to go bonkers. I'd check all the exhaust connections and pipes near the engine. Is the leak loud or just a subtle hissing sound? That might help pinpoint it.

Thanks! The exhaust leak is more of a subtle hissing sound. Since the error message specifically mentions the NOx storage catalyst aging, could the leak itself be the primary cause, or could it be a symptom of a failing catalyst?

Okay, subtle hissing points even more to a small crack or gasket issue somewhere near the manifold or the flex pipe. Honestly, I doubt the catalyst is actually 'aging' that fast. Those things are pretty robust unless they're exposed to extreme heat or physical damage. My money's on the leak throwing off the oxygen sensors and tricking the computer into thinking the catalyst is bad. I would recommend taking it to a workshop. I ended up paying about 265€ to get mine fixed.

I appreciate the explanation and advice. It seems best to have the exhaust system inspected thoroughly, focusing on potential leaks before thinking about a catalyst replacement. I will schedule an appointment with a trusted workshop to address this.