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Anyone know where I can start on finding these issues. I've checked for a vacume leak but don't see any...really dint know where to go from here. I've got a new dampener, but, all I see on YouTube us the passenger side not driver side...not worried much about this, More so, the P0171, U1950...any help is greatly appreciated..I'm also wandering if this causes my idle fluctuation.
Give us more data about your truck: Year, engine, mileage any recent repairs?
oh shat....sry...2007 F150 FX4 with the dreaded 5.5 3v....
210,000 miles just regular upkeep...aftermarket Air intake....stock on everything else...
repairs: just the entire front 4x4 drive...axles, IME's, hubs, etc... went ahead and put Bilstein shocks on while I was at it...that pretty much it...it's been a good truck!
Last edited by Bzak1pgh; Jan 11, 2025 at 11:35 AM.
P0171 (System Too Lean Bank 1): look for any vacuum leaks downstream of the MAF sensor, that is the most common cause for this code. You might also want to clean/replace the MAF sensor itself.
Less common causes for P0171 (but these would more likely also cause additional codes):
Low fuel pressure due to a restricted fuel filter, defective fuel pump, defective fuel pressure regulator, or defective fuel pressure sensor(s).
Clogged, dirty, or defective fuel injectors
U1950 (UBP Communication BusFault) : check the instrument connectors in the back in case they came loose and look for any signs of corrosion, there's a good chance water/moisture might've gotten in there. B1352 (Ignition Key In Circuit Fault): check all the fuses, grounds, and potentially replace the ignition switch (unless this could be somehow be related to U1950 ^)
P0171 (System Too Lean Bank 1): look for any vacuum leaks downstream of the MAF sensor, that is the most common cause for this code. You might also want to clean/replace the MAF sensor itself.
Less common causes for P0171 (but these would more likely also cause additional codes):
Low fuel pressure due to a restricted fuel filter, defective fuel pump, defective fuel pressure regulator, or defective fuel pressure sensor(s).
Clogged, dirty, or defective fuel injectors
U1950 (UBP Communication BusFault) : check the instrument connectors in the back in case they came loose and look for any signs of corrosion, there's a good chance water/moisture might've gotten in there. B1352 (Ignition Key In Circuit Fault): check all the fuses, grounds, and potentially replace the ignition switch (unless this could be somehow be related to U1950 ^)
Good luck!
Thank you!!!! I'll start checking everything u stated!!
Codes U1950, P0171
