2005 Seirra K1500 5.3L 86000 miles. Engine light is on, rough idle missing. It comes and goes but its becomming more frequent.

Shows running lean, O2 sensor, random missfire. It is missing on 1,3,5,7. have 55 lbs of fuel pressure. Mass air flow seems to be working ok. any ideas?

 

The problem is all on bank 1? You either have a leak in the intake on the driver side or an O2 sensor problem. For the latter, another member just went through a similar problem in thread https://chevroletforum.com/forum/tah...rplexed-48184/.

 

These are the codes it has been showing. I may not have it word for word:


P0171B Fuel trim system lean
P0300B Engine Missfire Detected
P0131B heated o2 sensor circuit Low voltage bank 1

 

They are all type "B" codes. I think P0131 is the key. Take a read through the thread I linked above.