Code P0172
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Freshman User
Joined: Dec 2014
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Code P0172
So my truck is reading a code at P0172 which means bank one is too rich. I replaced all of my o2 sensors, cleaned my MAF, and replaced PCV and hoses connected to it. What else could it be?
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Let me explain some things first.
The OX sensor only reported the issue, it's not the cause.
The MAF is common to both banks.
The PCV is also common to both banks.
.
That leaves you with a fault on bank 1, the passenger side.
The code actually is a response to the long term fuel trim table shifting 'lean' trying to counter the rich condition the Ox sensor detects.
You need to look for a possible leaking injector on one or more cylinders bank 1.
Excess fuel is the only way an over rich condition can happen.
If you use a Scanner to look at live data and the at long term fuel trim table, you will see it shifted more than 25%, setting the code.
This is all for the 172 code.
If bank 2 table is also shifted, then the rich condition is affecting that bank as well but to a lesser extent.
This is why it's good to look at live data to be sure of what you have.
Good luck.
The OX sensor only reported the issue, it's not the cause.
The MAF is common to both banks.
The PCV is also common to both banks.
.
That leaves you with a fault on bank 1, the passenger side.
The code actually is a response to the long term fuel trim table shifting 'lean' trying to counter the rich condition the Ox sensor detects.
You need to look for a possible leaking injector on one or more cylinders bank 1.
Excess fuel is the only way an over rich condition can happen.
If you use a Scanner to look at live data and the at long term fuel trim table, you will see it shifted more than 25%, setting the code.
This is all for the 172 code.
If bank 2 table is also shifted, then the rich condition is affecting that bank as well but to a lesser extent.
This is why it's good to look at live data to be sure of what you have.
Good luck.
Thread Starter
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Freshman User
Joined: Dec 2014
Posts: 27
Likes: 0
Okay bluegrass so yesterday i changed all my o rings on my fuel injectors and put the 4 injectors from bank one into bank 2 and that same code popped up again today. i checked all my hoses and they seem to be fine. i don't hear any whistling or abnormal sounds coming from my engine but my gas mileage is terrible right now. could it possibly be a converter or an exhaust leak detecting it? this code has been killing me. any other suggestions would be great!
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
The code is for a Rich condition.
It will affect fuel mileage.
Your last option could be a leaking fuel regulator.
From the diaphragm into the engine through the vacuum hose.
There has to be excess fuel for some reason and is being detected by the Ox sensor.
It can be verified with a Scanner looking at the long term fuel trim table for bank 2.
Good luck.
It will affect fuel mileage.
Your last option could be a leaking fuel regulator.
From the diaphragm into the engine through the vacuum hose.
There has to be excess fuel for some reason and is being detected by the Ox sensor.
It can be verified with a Scanner looking at the long term fuel trim table for bank 2.
Good luck.
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