I have a 2018 2.7 with around 89000 miles on it and had my 02 sensors go out changed them and I keep getting code low volt or not heating I have been trying to find a wiring diagram so I can try and hunt down my issues I have lost count of the times I have changed out the one it keeps telling me is the issue with aftermarket and oem and still the same .Please if anyone has had the same or close to it ...

 

You're asking for guessing!
What is/are the codes that you see, repeating?
The code description is the way to tell what is going on, not just that it is Sensor/s and keep replacing only to have the same issue again.
It may not be the Sensors.
Is it the Heater circuits that is failing? We need to know for sure what part of the function is in fault.
If it where me, my Scanner would tell me by looking at live data, in addition to the Code and descriptions.
Good luck.

 

@rbriggs70 Welcome to the forum.

 

 

There is only one Sensor at in fault.
Bank 2, rear Sensor for heating.
.
At every start-up the CATS are tested for Oxygen storage in a specified amount of time after starting for pass or fail.
Since that Sensor in on the output end, it returns the test result to the PCM.
The CAT may or may not be faulty until the Sensor heating fault is cleared.

The test involves cold start Ambient temps, rising to 800* then to 1200* and back to 800* during the test interval. This can be seen by Tach Action on the Dash and with a Scanner looking at Live data during that test time interval.
The Sensor has to be hot from its own heater and not depend on Exhaust heat for its function for this cold start testing. Ox test detection level is done is a different part of the Sensor.
It begins heating as soon as the ignition is turned on before engine cranks, under control of the PCM. The heating is actually controlled by the PCM as needed otherwise.
Good luck.