1997 F-150, 4.6L V8, keep fouling #3, #4, not oil, CHECK ENGINE LIGHT, code PO156, 02 sensor circuit malfunction (bank 2 sensor2), have replaced down stream 02 sensor and cats. NEED HELP PLEASE!!!!

 

Have you checked to see if the injectors are leaking?

 

yes, no injector leak

 

Are the wires good? What have you done besides replacing the O2 sensor? Please give us some history on the vehicle.

 

Here are some common causes for a P0156 code.

1. Pinched, shorted, and corroded wiring and pins
2. Crossed sensor wires
3. Exhaust leaks
4. Contaminated or damaged sensor
5. Bad PCM

Also, how did you check your injectors to see if they were leaking or not?