My van (2012 Express 4.3L) threw a P2270 code the other day (bank 1 sensor 2 lean). I reset it and it has not returned after a couple days of driving around. Same thing happed about 18 months ago. Has anyone else experienced this kind of behavior? Unfortunately I only have a cheap scanner than doesn't provide any real time data.

 

monitor the fuel trim for both banks at idle and underload when accelerating. if both banks are lean at idle...but ok under load...check for a vacuum leak. if ok at idle but lean underload....check the fuel pressure.

if only bank 1 is lean...replace that 02 sensor b1s2

lean fuel trim would show up at a % reading over 15%