Codes p0171 and p0174

SOURCE: diagonostic trouble codes reported p0171

P0171 is system too lean bank 1, P0174 is too lean bank 2, and 302 is misfire bank 1. Look for vacuum leaks. If you don't find them, put a vacuum gage on it can check. The P0171 is almost always a vacuum leak. If not other possibilities are front O2 sensor is too old and should be replaced (if mileage is greater than 100k then replace). Try injector cleaner. Misfires are usually bad spark plugs, but could possibly be caused by insufficient fuel. I've never had a car of mine in bad enough shape to have that error.

SOURCE: OBD codes P0171 and P0174

Look on the passenger side of the intake at the rubber elbow attached to the big black plastic tube and then to the intake manifold. Make sure it is not sucking shut and maybe a small hole in the bottom of it.

SOURCE: 2005 Ford Taurus SE 3.0L V6 OBD Codes P0171 and P0174

The P0420 code is a Catalytic converter efficiency code check the compression.Swap the #1 injector to a different location to see if the code follows.Test the coilpak. A cracked exhaust manifold is the most likely cause p0171 and 0174 Induction air leaks, vacuum or some kind fuel restriction, weak fuel pump, restricted fuel filter etc.You also could have an exhaust leak near the upstream o2 sensor. If youtake it in they will probably use smoke to find out where the leak is.

SOURCE: Mass Air Flow Sensor, oxygen sensor and coil plugs

I have codes 172 & 175 (Fuel trim bank 1 & 2, running to rich) So I was told to replace the Mass Air Flow Sensor. Easy install but very expensive ($150). We'll see if the service engine light comes back on.

SOURCE: 2001 Ford E150, V6. Stutter/hesitation upon

Have the throttle position sensor checked, might be faulty.