G Klasse check engine light and exhaust leak

It is possible that the exhaust leak is the culprit. The nitrogen oxides sensor measures the emissions after combustion. A leak upstream of the sensor may cause it to report incorrect values, triggering the check engine light and the error related to the NOx catalyst. Addressing the exhaust leak might resolve the issue. I had a similar problem with my G Klasse, but my expertise is limited.

Thanks for the input! When you say similar, was it the same error code and exhaust leak? How did you find the leak and what was the fix? I'm trying to gauge how deep I need to dig into this automotive repair myself.

Yes, same error code. Honestly, I didn't find the leak myself. I took it to a workshop. They used smoke testing to pinpoint the leak. It was a cracked exhaust manifold. They replaced it, and the error hasn't come back since. Given that you're hearing a leak, it is advisable to consult with professionals.

Appreciate the confirmation and the advice! I think I'll take it in to get checked out. I was hoping it would be a simple fix, but sounds like it's best left to those with more experience and the right tools. Hopefully, it won't break the bank. The estimated repair cost is 265€.