P0174 and P0171 then back to P0174 again!

Hi everyone!

Check engine light turned on, scanned it and said I had a P0174 code meaning engine running lean on bank 2 (driver side). I changed out the air/fuel sensor on that side and cleared the light. I drove about 60 miles and the light came back on. I got home and scanned it again and it now read that the passenger side was now running lean (bank 1) with the code P0171. Went to O'rielly and the guy said that since the driver side was new, it was tripping the other side which meant I would need to change the passenger side as well. I changed it, cleared the light, drove around, engine light came back on AGAIN. I scanned the truck once again, and now it was only showing the P0174 code again even though at this point both sides are new now...Thoughts? Should I keep driving the truck around for the computer to catch up or could it be another issue lingering?

Sorry for the long-ish post but I couldnt really condense what I had to say lol

 

Most likely the O'Reillys guy is full of bull as well as the sensors not being the issue. The light will stay out for a while because the monitor doesn't run right away but once it does it sets the code

 

When I took out the old sensors, they were pretty burned so it was time to replace them anyway. Should I just wait until the computer turns off the light and keep driving? I just changed the driver side last week, and the passenger side a few days ago

 

Were the old sensors really black?

 

not really, but they were brown on the verge of turning black? they just looked old honestly.

Ill try to upload a couple pics

 

Ok, You can keep driving it in the short term but I would have that looked into... Good luck!

 

Really need to look at fuel trims idling and driving to try to determine what's going on, 90% of the time it's not the O2/AFR sensors that cause lean codes.
Vacuum leaks, low fuel pressure, and dirty or skewed Mass Airflow sensor are ususally the primary suspect areas to check first.

 

i’m not sure if it’s the same universal code, but i think i had a similar code on my turbo subaru. i think it was a boost leak, means the intake manifold had a leak, and fuel/air that was entering the engine, wasn’t being accounted for by the MAF sensor, thus i had bad performance and that 0174 code.

look for a intake manifold leak.

 

hoses are good, MAF (gasket and sensor itself) is good, idk about the fuel pressure, maybe I should check that out then.

thanks for the reply !

 

thank you for the reply. I wouldnt be surprised as toyota and subaru have partnerships. Am I suppose to hear something when it comes to intake manifold leak?

 

not sure how to easily find a vacuum leak, usually you can find it by spraying the area that is leaking with carb cleaner or brake cleaner, the engine will make a noticeable change in rpm at idle, and possibly sound like it will stall.

some hard to find leaks can be found with a smoke generator. youtube is your best friend. i hope im not leading you down the wrong hole. good luck.

 

I got over 360k on my original O2 and AFR sensors. I had a P0420 code once and swapped the O2 sensors. But other than that, they've never been touched.

A bad gasket was the cause of my code. I found a tiny soot mark. That was all it took.

Scope things out carefully before loading the parts cannon

 

where was this gasket you speak of?

 

What do you mean they were "burned?" The actual sensor is inside the shield and is very hard to see. Are you talking about the part that is in the exhaust stream, and it having some carbon on it? That's normal.