P0171 Check Engine Light

Hello all!

I was driving yesterday and the dreaded check engine light came up. When I ran the code, P0171 popped up which caused me to open up the hood and find two of the vacuum hoses to be cracked/brittle. I went ahead and replaced them, hoping the code stays away after being cleared. What exactly do these two hoses do and would they be a potential cause for the check engine light?

https://imgur.com/a/2CQfi0D


Thank you Toyota family!

 

Those 2 hoses are vacuum hose for the PS.
There were mostly likely the cause of the p0171.
That code is for a system too lean, which will be set if vacuum hoses are disconnected.

 

When you turn the steering wheel the pressure switch opens and allows a little bit more air to raise the idle speed. With the hose off/plugged start the truck and turn the steering wheel a little, the idle will drop, put the hoses back and and do it again, the idle should stay steady or even go up. This little bit of RPM increase makes it easier to turn the wheel when the truck is at idle. As a FWIW… diesels are notorious for hard to turn steering wheels when parking, they idle so low that the power steering pumps dont put out enough pressure.

 

Yep....starving that pump while under max load.... with low rpms is a bad ideal....

 

Wow I had NO idea! Thank you for educating me on this topic!!

 

Update: Changed the hoses and CEL went away for good.