p2a00 all nissan diagnisti done no luck code come back in 5 milles any help

Question

emphasized text These car came with check engine ligth on and code P2A00 we replace 3 times (off Brand) the A/F sensor 1 bank 1 ,then we replace with the original from nissan no luck after all the time and wonk we remove intake plenium repace gasket injector seals and aii emision hoses ,check for intake Exaust leaks everithing is ok We dont know what else do all the wires was checked is fine we drive 4 miles ligth is on .(all the steps to check on nissan book was perfomed
Any Help Thank You

Answer 1

the SELF-LEARNING has to be cleared after the sensor is replaced. The easy way to reset the SELF-LEARNING is to disconnect the battery for at least 30min or so.

If that does not help the other possible causes are 

- Fuel pressure

- Fuel injector

- Intake air leaks