99 Ford Ranger throwing out code p0171

How does a vehicle throw up a code?, If it did you would have to clean it up. Codes are displayed, your PC does not throw characters onto monitor screen, it is displayed.
Trow is to propel (something) with force through the air by a movement of the arm and hand.
https://repairpal.com/obd-ii-code-p0171

P0301 is a engine misfire code for #1 cylinder , spark plug or plug wire problem or a bad fuel injector . Po171 system lean code . Lack of fuel , clogged fuel filter , vacuum leak . https://www.obd-codes.com/p0171 There are ways to test O2sensors before replacing . Your best bet take your vehicle to a qualified repair shop .

P0171 FORD - Fuel Injection System Too Lean Bank 1 https://www.autocodes.com/p0171_ford.html

P0301 FORD - Cylinder 1 Misfire Detected https://www.autocodes.com/p0301_ford.html

Here's a link on your code. http://www.obd-codes.com/p0171

PO171 is the 1st o2 sensor on bank 1. With that said a vacuum leak will also throw this same code so before I go changing an o2 sensor I would completely go over the engine and look for a vacuum line or intake leak. PO136 is the o2 sensor bank 1 the second sensor in the exhaust. Again here are some of the things that can cause this code. ( I always look for a vacuum leak somewhere first)

I bought a code reader and use it to cancel codes (When check light is on it puts the engine in a safe mode , affecting MPG ) I drive 600+ miles a month and the codes only throw 2 or 3 times , I have become good at canceling them on the fly with no noticeable problems. Just turned 200k and still runing strong

p1401 is your egr valve

YOU CANT TURN OFF PCM WHEN IT SPOT A PROBLEM.YOU HAVE TO FIX PROBLEM.BECAUSE THE CHECK ENGINE WILL STAY ON UNTIL PROBLEM FIX. ITS AGAINST THE LAW TO TAMPER WITH EMISSIONS SYSTEM.BECAUSE OF SMOG AND POLLUTION LAWS..HAVE TRUCK SCAN TO SEE WHAT YOUR PCM CODE IS.COULD BE SOMETHING MINOR.

Oxygeb sensor failure or EGR not working, bolcked passages.

Go to autozone and get failure codes for free if newer than 1996.

That's an 02/oxygen sensor code means that bank 1 or 2 is too lean. Good Luck contact if you need more help.