Cadillac ELR NOx Catalyst Failure + Exhaust Leak

Had similar symptoms with my 2019 Cadillac CT6 Hybrid last season. The exhaust leak and NOx emissions warnings ended up being more serious than initially suspected. The catalytic converter had developed cracks near the connection points, causing exhaust fumes to escape before proper emissions treatment. This affected both the air quality readings and overall emissions system performance. The diagnostic scan showed similar error codes related to the NOx catalyst efficiency. A thorough inspection revealed the leak was affecting multiple components: Damaged catalyst substrate, Compromised oxygen sensors, Deteriorated gaskets at connection points The repair required replacing the catalytic converter assembly and associated sensors to restore proper emissions control. This is not a repair to postpone, as it can lead to: Further damage to other exhaust components, Failed emissions tests, Reduced fuel efficiency, Potential engine performance issues Recommend getting a comprehensive emissions system inspection. Focus specifically on having them test the catalyst efficiency and check all connection points in the exhaust system. Request a smoke test to identify the exact location of any leaks.

Thanks for sharing your experience. That sounds exactly like what Im going through with my ELR right now. Those symptoms match mine perfectly, especially the location of the exhaust leak. Could you remember roughly how much the complete repair cost? Also curious if youve had any other issues with the NOx emissions system since getting it fixed? My fuel efficiency has dropped quite a bit and Im trying to budget for the worst case scenario before heading to the shop. Want to make sure I catch any related issues while its being serviced, since it seems this catalytic converter problem can cascade into other parts of the exhaust system.

Since getting my CT6 fixed, the emissions system has performed perfectly. The NOx storage catalyst aging problem was completely resolved after proper diagnostics and repair work. The leak in the exhaust system was actually less expensive than expected, coming in at 265€ for the complete fix including parts and labor. The automotive repair shop found the exact issue through pressure testing, and the catalytic converter repair restored my fuel efficiency back to normal levels. While your ELR might need slightly different work, the core issue sounds identical to what I experienced. The key was catching it early before the emissions system damage could spread. My nitrogen oxides readings are now consistently within spec, and Ive had zero issues with the exhaust system for the past several months. The repair cost was worth every cent considering the potential damage that could have occurred to other components. Make sure your mechanic checks the entire emissions pathway while they have it up on the lift. Sometimes what appears as a single exhaust leak can mask other wear points that need attention in the catalytic converter assembly.

Thanks everyone for the input. Just got back from the mechanic and wanted to share how it went. Finally got this sorted out properly. The automotive repair diagnosis confirmed exactly what was suspected, damaged NOx catalyst and leaking exhaust system connections. They did a full inspection and caught a few other minor issues that could have caused problems later. Total repair came to 320€, which included: New catalytic converter, Replacement of worn gaskets, Labor costs, Full emissions system test The fuel efficiency has already improved noticeably on the drive home. The exhaust system is working perfectly now with no more fumes or leaks. Also noticed the engine running much smoother, especially during acceleration. Good call on getting the comprehensive testing done. They found a small crack in one of the connecting pipes that would have caused bigger problems if left unchecked. The air quality sensor readings are all back to normal now. Really glad I got this fixed before winter. Definitely learned my lesson about getting unusual exhaust symptoms checked out promptly.