I have been trying to troubleshoot a P0131 & P0151 which is related to the Front primary 02 sensors on both Bank 1 and bank 2 AFAIK since having my vehicle seviced @ the Ford dealer for a PTU Flush & Trans fluid exchange on my most recent visit...
They did have to remove the passenger side DP due to the oil cooler in order to gain access to the temp sensor plus oil fill drain plug on the PTU on my PP-SHO....
So it's from my understanding if the readings on bank 1 are different from bank 2 then It will send you to one bank or the other, since the problem is in that bank telling me the issue correlates from one to the other! Correct me if I'm wrong! Z
I found a great article on the 02 sensors and more! I hope it helps someone decipher your concern in the very near future. Z
UEGO versus Oxygen Sensor
Some vehicles use a different type of upstream oxygen sensor known as a Universal Exhaust Gas Oxygen (UEGO) sensor. The EcoBoost V6 uses the UEGO sensors. This operates differently than a normal oxygen sensor. It provides a more robust (tolerant, less fluctuating) measurement of the air to fuel ratio. It uses the same Nernst cell to measure oxygen content in the exhaust gases.
Instead of comparing oxygen content to the outside air, it compares it to the oxygen content in a self-contained reference chamber. Like the old O2 sensor, it detects lean (more oxygen) and rich (less oxygen) exhaust, and the PCM makes an air-fuel ratio change.
The UEGO does not switch as rapidly or as much as a conventional sensor. At idle, you may not be able to detect any PID current flow (amps) movement at all. How can you tell if the vehicle has a UEGO sensor? Five wires run from the sensor instead of two.
Go to the IDS and check out what the datalogger recorded during the scan. The officer reported a driveability issue: lack of power during acceleration. Compare the seven PID values (volts, psi) at 1 second and then again at 15 seconds as the car is accelerating.
Sure enough, you can see the voltage change in the accelerator pedal position sensor, the cylinder head temperature sensor, and the throttle position sensor. You can see the fuel rail pressure in psi, and the manifold absolute pressure in psi, both change. And see the percentage of short-term fuel trim change. But what you don't see a change in from the one-second mark to the 15-second mark is the voltage on the throttle inlet pressure.
What does it mean when the UEGO readings on bank 1 are different from bank 2? It sends you to one bank or the other, since the problem is in that bank. PIDs for both sides of the UEGO are the same, perhaps a gasket or head. If the UEGO readings for both sides are the same, it means the fault is a system they have in common, perhaps a MAP sensor......
