Seat Inca NOx Sensor Issue

I had a similar issue with my Inca once. The check engine light came on, and the error code pointed to the nitrogen oxide sensor. The exhaust was louder than usual. Given the mileage, have you checked for damage to the exhaust system? A small leak before the catalytic converter can mess with the air-fuel ratio and trigger the sensor. The catalytic converter is important in pollution control. The sensor monitors the levels of nitrogen oxide after the catalytic converter.

Thanks for the quick reply! You mention a leak before the catalytic converter. How can I check for that myself? I'm not a mechanic, but I can handle basic stuff. How would a small leak affect the air-fuel ratio? I thought the oxygen sensors mainly controlled that.

If you have a leak in the exhaust system, unmetered air enters the system. This affects the air-fuel ratio. Your Inca will try to compensate, but may not fully correct for the added air. As a result, the nitrogen oxide sensor may detect incorrect readings and trigger the error. Although you may be able to find the leak, I suggest taking your Inca to a mechanic. They can properly diagnose the issue, check the exhaust system and catalytic converter, and test the nitrogen oxide sensor. A faulty connector is a plausible explanation.

Took it to the shop, and you were right. It was a bad connector on the NOx sensor. They cleaned it and replaced a bit of damaged wire. Cost 95€, much better than a new catalytic converter! Thanks for the help.