Colin_M

While I remember, on mine at least, one of the plastic nuts is smaller than the others which means it isn't retained on the undertray. I guess that's so that you have one hole available to get the panel located onto the bolts on refitting, rather than having to guess whether everything is in the right place.

A 10mm socket does the job. The nuts are plastic and should stay in place on the undertray because of the lugs.

My 2019 2.0 diesel Karoq has the engine warning light on, and my diagnostic app reports U029E, which is "lost communications with NOx sensor B". I guess this will either be a failure in the sensor module or a cable / connector fault. Is there any common / typical cause behind this fault code, e.g. the sensors are known to fail easily, or the connectors are susceptible to water damage? Also, if I ignore it fir a while will anything actually be affected?