Question

2009 Ford F250 5.4L with engine codes P0191, P0171 and P0174

Answer 1

HI there

P0171 and P0174 mean there is a lean fuel mixture on bank 1 and bank 2.

P0191 is a code for the fuel pressure sensor, so basically it looks like you have low fuel pressure which could cause the lean fuel mixture codes. I would start by checking the fuel pressure.

P0191 FORD - Fuel Rail Pressure Sensor Circuit Range/Performance
Read more: https://www.autocodes.com/p0191_ford.html

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

P0174 FORD - Fuel Injection System Too Lean Bank 2
Read more: https://www.autocodes.com/p0174_ford.html