Mercedes M Klasse Check Engine Light and NOx Sensor Issue

I had a similar issue with my Mercedes The exhaust leak could be messing with the readings When my NOx sensor went bad, it messed with the air-fuel ratio, which can hurt the catalytic converter and pollution control Have you checked the wiring to the sensor Corrosion or loose connections can look like a sensor failure Also, check the catalytic converter itself A bad catalytic converter can trigger NOx sensor errors

Thanks for the reply Where exactly should I look for corrosion or loose connections in the wiring harness What diagnostic tools or methods do you suggest for checking the catalytic converter beyond just looking at it, especially regarding the air-fuel ratio

Check the connector pins on the wiring harness Make sure they're clean and making good contact Use a multimeter to check for breaks or shorts in the wire For the catalytic converter, a back pressure test can show if it's clogged Some tools can measure the oxygen storage capacity, which tells you how healthy it is Since this can get complex and affect pollution, a qualified workshop is a good idea They have the skills and tools to diagnose it right

Thanks for the advice I went to a workshop They found a bad NOx sensor and a small exhaust leak near the connection, which caused bad readings They replaced the sensor and fixed the leak The check engine light is off now and it runs great Thanks for your help