Ford Focus NOx Sensor Failure

Hey, I had something similar with my Focus. Though it was a while back, I remember the check engine light and some weird readings. Did you check the sensor connections? Is the air-fuel ratio off, or do you smell unburnt fuel? It could be pollution control related.

I visually inspected the connection and it looks ok, but how can I be really sure? And how did you pinpoint the NOx sensor as the problem?

Well, in my case, the connection looked fine too, but the error code was pretty clear about the NOx sensor. I'd recommend taking it to a workshop to get a proper diagnostic. They have the tools to check the sensor's readings and the wiring properly.

Thanks for the advice. I took it to the workshop and you were right, the NOx sensor plug was defective. The repair cost me 95€. All sorted now!