P0171 on a 2016 Ford F 250 Super Crew

P0171 means the engine computer is adding more fuel than normal on bank 1 because it sees too much air or not enough fuel.

Not your vehicle? See general P0171 info.

Most common causes on the 2016 Ford F 250 Super Crew

Ranked from 287 NHTSA owner complaints filed for this vehicle.

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1
Clogged fuel filter
High severity
One owner's fuel filter clogged badly enough that fuel sprayed from the filter housing while the truck ran, showing this is a real, hazardous restriction failure mode on this truck.
Reported in 1 NHTSA complaint
Parts:fuel filter
2
Weak or failing fuel pump
High severity
An owner lost power and control in a corner when the fuel pump failed outright, confirming fuel-delivery pressure loss as an active failure mode on this vehicle.
Reported in 1 NHTSA complaint
Parts:fuel pump
3
Vacuum/intake leak requiring intake manifold repair
Medium severity
One owner had the intake manifold replaced after a driveability complaint, consistent with an unmetered-air leak leaning the mixture.
Reported in 1 NHTSA complaint
Parts:intake manifold gasket
4
External fuel line leak reducing delivery pressure
High severity
An owner smelled diesel fuel and found the source was a leak that led to an engine-compartment fire; a leak upstream of the injectors can reduce delivered fuel pressure/volume.
Reported in 1 NHTSA complaint
Parts:fuel line
5
Dirty or failing MAF sensor
Medium severity
A contaminated or drifting MAF sensor under-reports intake air, causing the PCM to under-fuel and trip a lean code.
Common cause
Parts:MAF sensor
6
Turbocharger boost/charge-air leak
Medium severity
A leak in the charge-air piping reduces effective air/fuel calibration accuracy and is a common diesel-specific lean-condition cause.
Common cause
Parts:turbocharger intercooler hose

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These causes are aggregated from NHTSA owner complaints and general repair knowledge — this is not a diagnosis. P0171 on your car still needs shop confirmation before any repair.

Common symptoms

Check engine light
Rough idle
Hesitation
Surging idle
Poor fuel economy

What to check before replacing parts

Review short- and long-term fuel trims on bank 1

Look for: High positive trims (commonly worse at idle, improving with RPM) mean the computer is adding fuel to compensate for excess air or insufficient fuel — that pattern is this code's fingerprint.

Smoke-test the intake

Look for: Smoke escaping (or a hiss you can hear) at intake boots, gaskets, or vacuum hose connections confirms unmetered air is entering after the MAF sensor, which is the most common cause of a lean code.

Inspect the PCV hoses and valve

Look for: A cracked, split, or disconnected PCV hose, or a PCV valve stuck open, draws in extra unmetered air the same way a vacuum leak does.

Clean and test the MAF sensor

Look for: Visible dirt or oil film on the sensor element, or a grams/second reading that doesn't track expected airflow for RPM, means the MAF is under-reporting air and causing the computer to under-fuel.

Verify fuel pressure

Look for: Pressure below spec (weak pump, clogged filter, failing regulator) starves the engine of fuel and produces the same lean trim pattern as a vacuum leak — rule it out before chasing leaks.

Rather have a pro handle it? Find a vetted local mechanic.

Matching symptoms

Car Runs Rough