Error codes P0171 and P0174

2002 FORD F-450
233,000 MILES • 4.0L • 6 CYL • 2WD
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AWALTHER1
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Check engine lights on! When I fix the problem will the light go out on its own?

Error codes P0171 and P0174.
I will clean the MAF module and look for large hose vacuum leak. Maybe replace fuel filter.
Aug 16, 2018 at 3:01 PM
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AWALTHER1
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Change truck information to F150 not F450.
Aug 17, 2018 at 5:28 AM
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ASEMASTER6371
  • ✓ASE Certified Mechanic
  • 52,796 POSTS
  • ASE Certified Mechanic
Good morning.

These two codes indicate a lean running engine.

The most common issues are low fuel pressure and vacuum leaks. I attached possible issue below for you.

Roy

P0171
Descriptor
System To Lean (Bank 1)
Probable Causes
Cam Timing
Cylinder Compression
Exhaust Gas Recirculation (EGR) Valve Stuck
Exhaust Leaks Before or Near Heated Oxygen Sensors (HO2S)
Fuel Injectors Leaking or Contaminated
Fuel Pressure Excessive
Fuel Pressure Regulator Leaking
Gasket Leaking
Improperly Seated Engine Oil Dipstick
Leaking Diaphragm or EGR Vacuum Regulator (EVR)
Low Fuel Pressure or Running Out of Fuel
Oil Overfill
Positive Crankcase Ventilation (PCV) System
Vacuum Leaks
Vapor Recovery System
Aug 17, 2018 at 7:23 AM
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AWALTHER1
  • MEMBER
  • 3 POSTS
Check engine lights on! When I fix the problem will the light go out on its own?
Aug 17, 2018 at 8:43 AM
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ASEMASTER6371
  • ✓ASE Certified Mechanic
  • 52,796 POSTS
  • ASE Certified Mechanic
If you correctly repair the issue, the light will clear itself in fifty key starts with no recurring issues.

Do you know the long term trim readings?

Roy
Aug 17, 2018 at 8:47 AM
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