Reading Lean/ Bank 1, Is it O2?

many things can cause a lean code. first thing you need to do is get live data readings from the PCM and check these too pids..

LTfueltrim bank1 and LTfueltrim bank 2

if they are both lean but bank 2 has not set a code then you most likely have a vacumm leak or a maf problem..

if only bank 1 is lean then you could have exhaust leak on that bank.. or a misfire on that bank will cause one bank to read lean since the 02 sensor only picks up the unburn oxygen of a misfire.

BTW 999 out of 1000 times lean codes are not o2 sensor problems.. in fact I have never seen a lean or rich code fixed with 02 sensors. the way the PCM stragy works if the sensor is bad you will most likey get a sensor indicates lean or rich code.. this is a different code than the po171 lean bank one code..

One last thing.. replacing the one reamining sensor on the drivers side ( bank 2) will nto fix this problem.

Check for an exh leak also, fwd of the O2 sensor, had it happen to me.

OV10stang said:

Check for an exh leak also, fwd of the O2 sensor, had it happen to me.

Click to expand...

yeah I said that too. if it's only lean on bank one then thats the most likely cause. ( you must verify this with a scan tool.. it may only have bank 1 code but bank 2 might be at + 23 fuel trim and about to set a po174 lean bank 2 any minute)