I have a 2010 Land Rover lr4 and noticed high short term fuel trim around 20% at idle. Rev the car up, it drops down to an acceptable range. The first time I did a smoke test revealed a leak at the valve cover gasket that was also confirmed by the oil dripping on the alternator! I replaced both valve cover gaskets myself. I thought for sure that would cure it. Next, I tried to smoke test either at the throttlebody or on one side of the resonator with the other side plugged up, could not find any smoke, except the most minute trace amount where the resonator attaches to the throttlebody. With the car running, I used carb cleaner to spray it in the exact spot with no RPM change and all over the top of the engine, including the PCV valves. Also replaced the PCV valves! So I cannot find any type of smoke leaking out of the system Also has newer spark plugs. I even replaced the battery which had questionable voltage.

So the only thing left that I’m wondering about is the O2 sensors, but I really don’t know how to monitor them with my OBD scanner. With 200,000 miles these are original O2 sensors. Can anyone give me guidance on where you would be looking?

I have an icarsoft scanner and I did notice an occasional misfire on cylinder two and four. The computer has some kind of function that keeps track of misfires that are “ catalyst damaging” but for the smog readiness, the misfire counter has already cleared as one of the parameters that the computer says is OK for smog.

Please help me. Attached is a screenshot of the O2 sensor and it a bit One is tenfold greater than the other