V6 4.2l engine codes
 

I have the following problem:
Check engine was on so I got the folowing codes
P1131 p1151 p0171 p0174.
I did replace MAF and the car is running a lot better but the engine is Pinging badly. It was not doing before. On top of that the check engine light was on again but only two codes sowed up: P1131 p1151
Please help

P1131 Lack Of HO2S11 Switch - Sensor Indicates Lean
P1151 Lack Of HO2S21 Switch - Sensor Indicates Lean

thats what the codes read

I would do a thorough inspection for a vacuum line off or any other cause of a vacuum leak downstream from the MAF sensor.
Check the PCV valve and all vacuum lines. Seems most often lean codes are due to vacuum related leaks.
I'd also disconnect the battery for 5-10 mins to clear the OBD II code and reset the ECM computer.
Then crank the truck and drive normally to see what happens.

Here's some more info:
https://www.ford-trucks.com/tsb/full...hp?tsb=05-22-6

Let us know what you find (if anything).

Thanks.