P0171 on a 2019 Ford F 250 Supercab

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 2019 Ford F 250 Supercab

Ranked from 1,151 NHTSA owner complaints filed for this vehicle.

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1
CP4 high-pressure fuel pump failure
High severity
Overwhelmingly the dominant pattern in this batch: owners describe the factory CP4 high-pressure pump (the same design later recalled on 2020-2024 trucks) failing and sending metal debris through the fuel system, causing loss of fuel pressure/delivery.
Reported in 10 NHTSA complaints
Parts:high-pressure fuel pump fuel injector fuel rail
2
Failing lift/transfer (low-pressure) fuel pump causing hard starts
Medium severity
Many owners describe long cranks, hesitation, or complete no-start/stall conditions pointing to inadequate low-pressure fuel supply feeding the injection system, independent of a confirmed CP4 failure.
Reported in 7 NHTSA complaints
Parts:fuel lift pump fuel filter
3
Fuel line or fuel filter housing leak/crack
High severity
Two owners had a fuel line separate from the fuel filter, causing a loss of fuel pressure and, in both cases, a fuel fire.
Reported in 2 NHTSA complaints
Parts:fuel line fuel filter
4
Charge air / intake boost leak
Low severity
A leak in the charge air path admits unmetered air similar to a vacuum leak on a gasoline engine, upsetting the commanded air-fuel ratio.
Common cause
Parts:charge air cooler hose intake boot
5
MAF/MAP sensor fault
Low severity
An inaccurate mass airflow or boost pressure reading causes the PCM to miscalculate fueling, producing a lean-type trim code.
Common cause
6
EGR valve fault
Low severity
A stuck EGR valve changes the intake charge composition enough to skew fuel trim calculations.
Common cause
Parts:EGR valve
7
Turbocharger boost leak
Low severity
Reduced boost from a leaking turbo connection lowers available airflow/fuel scheduling accuracy, which can present as a lean-trim code under load.
Common cause
Parts:turbocharger

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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