P2196 b1s1 stuck rich
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Bank one is passenger side on a sohc 4.0
You said you replaced the bank 1 sensor 1 already? When you did was the wiring inspected?
If the sensor was replaced the code was cleared and it came back then
You
Likely have a rich condition but only on one bank of cylinders
This would indicate an issue with an injector
It is not
Likely to be an ignition issue, although having a look at the 3 plugs on the passenger side
Might help determine which cyl is having issues.
It’s not likely to be a fuel pressure issue because it only effects one bank
It is very likely an injector is stuck open or just dripping fuel
You should visually check the injectors on that bank as much as possible, no wiring damage? Everything plugged in?
Sometimes we can listen to the injectors click as they open and close with the engine running
Let us know what you find