Error Code 171

My Check Engine Light came on while traveling on the freeway while climbing a hill. My Scanguage II tells me that the stored error code is "PO171 System too Lean (Bank 1)"
Why would my system be too lean? What can I do to richen it up to where it's supposed to be?
Jerry

 

Get it checked out. Could be several things. Do you understand how to read scan data under regular driving conditions?

If not, you could end up guessing and spending money without a fix.

 

You say "Get it checked out." Kinda makes you sound like a Toyota dealer wanting me to "Get it checked out."
I'm trying to check it out by posting here. Do you have an answer to my question?
Jerry

 

How many miles on your truck? I would try cleaning your MAF sensor, might just be dirty.

 

I did answer your question. Anything you are told on here, for that code, will be a guess. A P0171 code is set when the vehicle has reached adaptive limits for fuel control. It has added fuel to the base table until it is outside an accepted range. There can be several reasons for this. It would depend on what the fuel trims are under different driving conditions. Where the trims are out of range is the first clue to the root cause and can only be seen on a test drive with the correct equipment. Then some tests to verify the root cause and then the repair. If you toss a part at it that is a couple hundred dollars and it does not fix it, "checking it out" would be the cheaper route.

I am not a Toyota dealer or a Toyota tech. I am a CMATL1 certified technician and an automotive diagnostics instructor.

Sorry my answer did not fit your expectations. Guess away. Could be as simple as a clogged fuel filter, a tank of gas with a high ethanol content or as expensive as an AFR sensor or failed MAF. Pick a starting place and spend away. You said it was under high load (climbing a hill on the highway) so start with the items that would be important under those conditions.

 

ShadowFalken is exactly right. P0171 is a system too lean code, or in laymans terms, their is too much fuel returning to the gas tank. I am a Toyota tech, and it's more than likely a Mass Air Flow Sensor malfunction. However, there are other things too check, such as vacuum leaks, before you go throwing money at your truck.