Lexus RX NOx Sensor Failure

Hello! A NOx sensor issue on a hybrid RX is not uncommon. The smell of exhaust suggests a potential leak which could indeed be linked. Have you inspected the sensor's cable and plug connection thoroughly? A defective connection, even if visually intact, can cause intermittent or constant errors. Also, consider the catalytic converter's condition. Although less likely, a failing converter can influence NOx sensor readings. What about the air-fuel ratio, have you checked it?

Thanks for the quick reply! When you say check the cable and plug connection thoroughly, what exactly are you suggesting? Just wiggling it around and hoping for the best? I'm also not sure how to check the air-fuel ratio myself - is that something I can do with a basic OBD2 scanner, or do I need more specialized equipment? As for the catalytic converter, is there a simple way to check its condition without pulling it apart?

By 'thoroughly,' I mean carefully examine the connector pins for corrosion or damage. Sometimes, they can be bent or pushed back. Also, check the wiring for any breaks or fraying, even under the insulation. Regarding the air-fuel ratio, a decent OBD2 scanner should display live data. Look for any unusual fluctuations or consistently lean/rich readings. As for the catalytic converter, a failing one usually causes other symptoms alongside the NOx sensor error. Given the exhaust smell, it's more likely a connection issue. I suggest you visit your local mechanic, they could identify the error cause.

Thanks, that's super helpful! I'll take another look at the connector with a magnifying glass this time, and see if I can get some live data from the OBD2 scanner. If that doesn't turn up anything obvious, I will schedule a visit with my mechanic as you suggested. By the way, it was a cable and plug connection of the component defective. The repair cost 95€. Really appreciate the help!