Have a 98 V6 throwing a P1151 (HO2S21 sensor indicates lean) and a PO174 System Too Lean(Bank 2). What is causing this? An O2 sensor? Which one? Anyone know?

Thanks Rob

 

ok there T444E powerstroke diesel i bet you didn't think anybody here could figure you name out.

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it is most likely an upstream from cat O2 sensor.

it may be an injector falling behind in flow rate.

my bet is sensor

 

Rh or Lh side, which one is Bank 2?

 

drivers side is bank 2