P0171 on a 2019 Jeep Wrangler Unlimited

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 Jeep Wrangler Unlimited

Ranked from 725 NHTSA owner complaints filed for this vehicle.

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1
Recurring high-pressure fuel line failures reducing fuel delivery
High severity
This vehicle's high-pressure fuel line has ruptured and been replaced multiple times, cutting fuel pressure/delivery to the rail and skewing the mixture lean; also a fire-risk safety issue.
Reported in 2 NHTSA complaints
Parts:fuel line
2
Weak or failing high-pressure fuel pump
High severity
The high-pressure fuel pump was directly diagnosed as malfunctioning and requiring replacement on this vehicle, a classic lean-condition cause.
Reported in 1 NHTSA complaint
Parts:fuel pump
3
Vacuum or intake air leaks
Medium severity
Cracked hoses or gaskets, especially around this engine's turbo plumbing, admit unmetered air.
Common cause
Parts:vacuum hose intake gasket
4
Dirty or failing MAF sensor
Medium severity
An under-reporting MAF causes the PCM to under-fuel relative to actual airflow.
Common cause
Parts:mass airflow sensor
5
Stuck-open PCV valve
Low severity
A PCV valve stuck open acts as an unmetered air leak into the intake.
Common cause
Parts:PCV valve
6
Intake manifold gasket failure
Medium severity
A failed gasket is a direct unmetered-air path into the intake tract.
Common cause
Parts:intake manifold gasket
7
Exhaust leak upstream of the O2 sensor
Low severity
A leak ahead of the sensor draws in outside air that gets misread as a lean condition.
Common cause
Parts:exhaust gasket

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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