P0171 on a 2019 Ford F 250 Regular Cab

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 Regular Cab

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

Sort by:

1
High-pressure fuel pump (CP4) failure
High severity
An extraordinary number of owners in this batch report the factory CP4 high-pressure pump failing and sending metal shavings through the fuel system, causing stalls, hard starts, and reduced power — a well-documented issue on the 6.7L Powerstroke that starves the engine of fuel pressure.
Reported in 18 NHTSA complaints
Parts:high-pressure fuel pump
2
Fuel injection pump wear/defect
Medium severity
One truck was diagnosed with a defective fuel injector pump causing excessive engine wear and damage.
Reported in 1 NHTSA complaint
Parts:fuel injection pump
3
Vacuum, intake, or charge-air (boost) leak
Medium severity
Unmetered air entering after the MAF sensor skews the fuel trim lean; check intake boots and boost hoses.
Common cause
4
Dirty or failing MAF sensor
Medium severity
A contaminated or drifting mass air flow sensor under-reports incoming air, causing the PCM to under-fuel.
Common cause
Parts:mass air flow sensor
5
Stuck-open PCV valve
Low severity
A PCV valve stuck open admits excess unmetered air into the intake.
Common cause
Parts:PCV valve
6
Exhaust leak upstream of the O2/fuel-trim sensor
Low severity
An exhaust leak ahead of the sensor draws in outside air and biases the reading lean.
Common cause
7
Intake manifold gasket failure
Low severity
A leaking intake gasket is a common unmetered-air source on higher-mileage trucks.
Common cause
Parts:intake manifold gasket

Part links go to Amazon search results for this vehicle. As an Amazon Associate, WrenchConnect earns from qualifying purchases — always confirm fitment for your exact trim and engine before ordering.

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