Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
So from the beginning. The vehicle came in running super duper rich with misfires and exhaust black. Had bad oxygen sensor commanding rich which fixed the concern and runs smooth now.
Now, I get p0172 and p0175. Reviewing fuel trim long is steady -10 to -15 more on bank one and 2 shows -5 to -13. Short trim -5 to -10 both banks.
Oxygen sensor readings before the cat show great reporting. Oxygen sensors after cat bank 1 when warmed up shows a steady rich. Bank 2 sometimes rich and sometimes reports normal. Do I have bad cats due to it previously running rough and rich? Would that cause my p0172 and p0175? It’s interesting to see the bank 1 sensor 2 show a steady rich concern when warmed up when the sensor 1 is operating normal. I changed the sensor with the same reading. Also, sensor 2 looks good until warmed up
There could be cat damage. But, my first suspicion would be excessive fuel in the oil and crankcase. That'll get sucked up by the PCV system, and you end up with rich trims. This is very likely if your customer was driving around with the rich condition for any length of time.
You could eliminate the PCV system from the intake to confirm this. Or, just change the oil on general principle and see if the trims improve afterwards. :lol:
The cat fixed the too rich issue on bank 1. BANK 2 still showed too rich. Did the oil change (very bad fuel smell) with no change on bank 2. Had bad fuel injector that fixed bank 2 too rich.
