kreyszig

Hi everyone. This is my first post on this forum. I have similar issues with my Forester SOHC '10 and I came across this thread. I noticed that the thread was started a long time ago, but since they are relatively recent posts, I thought it might be ok to post my question here... So my Forester has 152,000 miles, driven in Ontario, Canada. I recently got the P2097 code, which led me to replace the rear O2 sensor, the first sensor to be replaced on this car. Obviously the code came back, so I got a better reader with live data capabilities. I am attaching a CSV file that contains data from a ride I just did with the car. I have included data for the two sensors, the MAF and the MAP. It was 21F outside, but the engine was still warm when I started it. My understanding is that the front (wideband) O2 sensor reads about 5% too lean (lambda=1.05), while the new (narrowband) rear sensor reads too rich (0.94V). The long fuel trim around 10% would indicate that the ECU is adding more fuel than normal. Based on a lean front sensor and a rich rear sensor, does it mean that there is definitely something wrong with the front sensor, unless my new rear Bosch sensor is defective? Could a band MAF cause this issue (I don't see how that would be possible)? Note that the spark plugs and the air filter need to be changed soon (although I also do not see how this could cause these particular values from the sensors). Thanks for your help! BDDataLog.csv