We have a 99 ford ranger 3.0L flex fuel and it is throwing system too lean bank 1 & bank 2 codes, P0171, P0174...we have replaced 02 sensors, mass air flow sensor and have paid for 2 diagnostic tests and they can not find a thing...it keeps pointing to mass air flow sensor. What to do?

P0171 system too lean bank 1
P0174 system too lean bank 2

You aren't getting enough fuel to keep car running and the system shuts car down

P0171 ; Fuel Trim System Lean (Bank 1)
P0174; Fuel Trim too Lean (Bank 2)
fuel trim is system to modify injector pulse if system go lean it will go rich when the system is too much lean and is max.rich it code
look for 02 sensor bank 1 and 2 data
hope it helps

Hi Donna,here's a link to your code. P0171 Ford Fuel Injection System Too Lean Bank 1 .Here's a video. How to Diagnose OBD II Fault Codes P0171 and P0174 Leaking Intake and...

fault code p0171 is system too lean bank 1.................. intake/exhaust leak. air system MAF/VAF sensor. Fuel pressure/pump , injectors HOS2.

fault code p0174 is system too lean bank 2...................intake exhaust leak, fuel pressure/pump , injector(s) Air system, Hose connectors

hope this helps you

Hi hope I can help.
P0171 mean bank 1 is to lean
P0174 means bank 2 is lean
You did not state what engine you have but by your codes you must have the V6 4.0.
These codes refer to a fuel issue. bank 1 and bank two represent each of your manifolds.
being you have a V6 you have 2 manifolds.
Each of your manifold have an O2 sensor in it. That's what is giving the lean reading.
This does not mean that you have bad O2 sensors.
They are just doing there job.
So you should check your fuel pressure with a gauge and make sure your pressure is correct.
It seams as your fuel pump maybe weak.
Hope this helps.
Please leave feed back
Thank you urnuts73@ FixYa

Hi, 1151 is an 02 sensor code, 1131 is also 02 sensor code,
0174 lean condition bank 2, and 0171 is lean bank 1. Either this is in need of a whosale of repairs or you have computer issues, From looking at the codes i would first do a complete tune up, Including wires, And inspect for a vacume leak before replacing any 02 sensors..
Take care

P0171------ system too lean bank#1
Po174------ system too lean bank#2
For these 2 codes, try cleaning the maf sensor (mass air flow), that is mounted in the big black hose that goes from the air filter housing to the throttle plate, if it is dirty, that will cause those 02 sensors to send a signal to the computor to lean the air fuel mixture. If cleaning it doesn't work, the sensors will probably need changing.
P0300---- Random/multiple cylinder misfire
P0316---- Cylinder misfire at start up---- first 100 revolutions.
On those 2 codes, you have to do some testing to find out why there is a misfire.
Possible causes:
dirty/malfunctioning injectors
weak coil pack
fowling spark plugs/wires
Low fuel pressure

Those codes are for the oxygen sensors, lean fuel mixture on both banks. Change them, problem with stalling and rough idle should go away.

Hi
171 system too lean
174 system too lean
2195 - 02 ozygen sensor signal stuck lean Bank1 Sensor 1
2197- 02 ozygen sensor signal stuck lean Bank 2
Sensor 1
The 2 front 02 sensors are located on the front of
the exhaust manifold.
Should solve problem and increase gas mileage.

Bank one is toward the front of the vehicle. Sounds like the heated oxygen sensors have gone bad. The Oxygen Sensors are located in the exhaust pipe and require a special socket to remove and replace.