P0172 and P0175 codes.... Any help?

Hi all,

2016 Tundra Platinum w/ 5.7L Flex 4x4 at 130K miles.

Has anyone seen these codes and have a solution for P0172 and P0175? "Banks 1 and 2 running too rich"

I've already replaced the MAF, cleared codes and after about week they came back. I did a visual check for vacuum leaks, but can't ID anything. Seems like both O2 sensors going out at the same time would be highly unlikely. IDK?

Any ideas or solutions?

 

Vacuum leaks would cause the engine to run lean, not rich. You are either getting too much fuel or not enough air. I'm not very familiar with the flex fuel trucks, but I know E85 requires a richer mixture, so there could be something going on there.

1) What prompted you to replace the MAF?
2) Did you replace with an original part from Toyota?
3) How does your air filter look?
4) What fuel are running? Did the light come on after filling up?

 

Hi, good point on vacuum leak but was thinking a leak might cause ECU to overcompensate? ‍I get that it’s getting too much fuel, but what could cause that?

Answers:

1. My logic was that bad MAF may cause poor fuel/air mix with ECU, and this issue was referenced in other chats. Worth a shot?
2. Not OEM, used a Bosch. I still have OEM I can swap back easily. 3. Filter is basically new
4. Use regular 87oct unleaded. I’ve never used any Flex fuel in it. It’s just rated for it.

Thanks for reply…any help is appreciated.

 

Basically if the engine is getting less air in (or thinks it is getting less air) it will reduce the amount of fuel injected. However its programmed with limits, so if it sees that it needs to keep going lower it will throw a rich code. Opposite would happen if there was a vacuum leak, it'll add fuel to a point and then throw a lean code.

As far as a cause there could be a restriction in the intake (like a clogged filter) or bad sensor. Could also be injectors that are stuck open, but that seems unlikely to happen on both banks at the same time. Another highly unlikely cause is too much fuel pressure.

I'd try cleaning the MAF with the correct cleaner and popping the OEM one back in first. Also leave the battery unhooked for a bit after swapping the sensors. I'd check your intake tubes in the fender area and airbox as a well as double check the air filter.

Do you have a copy of Techstream or some way to look at the fuel trims?

 

Thanks! I’ll look for obstructions first and see if there’s anything obvious.

I don’t have techstream, just a good code scanner but it does live fuel scanning too I believe. I’ll have to do a little research as I’ve never done that before, so I’m not sure what to look for in terms of data.

 

I've got the same codes on my first gen.