Looking for a little help...

[Justin Tilton]

2015 Yukon. Throwing a P0172 code. 

I have changed the MAF and MAP sensors. No change. 

If I clear the code, it comes back within 15 minutes of driving. There is also a very noticeable fuel smell. The engine will also shake (shudder) after shutting off. 

 

Looking for anyone thats dealt with this and had the same issues. I know P0172 can be many things. I dont want to replace everything trying to figure out what it is. Any help would be great! 

[CamGTP]

The code is for a rich condition so that bank is seeing a lot of extra fuel. Usually that is going to mean something wrong with the injector(s) on that side. Rarely is it the o2 sensor itself but it can happen.

 

When you said that the engine will shudder/shake when you shut it down that kinda says to me that it's dieseling from the extra fuel. Injector failures are pretty darn common on these engines.

Edited March 28, 2023 by CamGTP

[Grumpy Bear]

Get a GC fuel run on the oil. A little goes a long way to killing the viscosity. @Black02Silverado can help with that if you chose. 

[richard wysong]

Welcome to the Forum! Codes do NOT mean start replacing parts, they are the start of the diagnosis process, The service manual and Alldatadiy have diagnostic trees for each code to follow to find the problem without firing the parts cannon. Cam is probably right on with the bad injector. Make sure you change the fuel diluted oil ASAP

Edited March 28, 2023 by richard wysong

[Justin Tilton]

Thanks for the replies. Researching more on it last night, I agree its a fuel injector or High Pressure Fuel Pump. Is there a good way to tell which one it would be? I have spoken to someone that had the same dieseling after shut off. His ended up being the fuel pump. But also read rich on both bank 1 and 2. Mine has only been showing bank 1. Would this be any indication that its an injector on that side instead of the fuel pump? 

Edited March 28, 2023 by Justin Tilton

[Justin Tilton]

Update for anyone that runs into this issue. I replaced the high pressure fuel pump and it solved the issue. 

[Grumpy Bear]

1 hour ago, Justin Tilton said:

Update for anyone that runs into this issue. I replaced the high pressure fuel pump and it solved the issue. 

 

Lord that is a lot of fuel to go rich from PCV return. Good catch and early too it seems. 

 

Now change that oil  

Edited April 18, 2023 by Grumpy Bear