Unfortunately this has popped up on my partners J10 Nissan Qashqai 2008, I recently had a P0420 fault code although after replacing the o2 sensors it seems to have disappeared after clearing now being replaced by a P0303, Car has been sitting for 2 weeks whilst I changed oil,Brake pads and o2 sensors, Decided to take it for a run today for 30 miles and had this sitting in the pending codes twice even after clearing. So I’m expecting it to show the EML at any moment.
Anyone have experience with this? Did check through the service manual which mentioned to check the o2 sensors along with a bunch of other stuff, Can’t see it being the o2 sensors as the readings seemed within normal tolerances.
Having experienced similar issues in previous cars I know this can get really costly, So I’m after some advice on probable causes first rather than going start to a garage to get some bs like a timing sync issue.