So I'm having this issue with my car and it only happened after I left it for around 2 months without driving. There is check engine code P171 saying System running too lean. I connected OBD2 reader and managed to get some test results, everything passed except this:
MID: $3c TID:$81
EVAP Monitor (0.040")
Min: 90.25Pa Max: 8,191.75Pa
I reset the codes to see when exactly it occurs, I drove about 120 miles on it and nothing came up. All tests other than the catalyst test were complete (including evap system tests) and no code was present. Once the catalyst tests were completed, the code came back.
Could the vacuum leak be causing this code, or is it more likely to be the O2 sensor?