P0171 on a 2018 Jeep Grand Cherokee Trackhawk

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 2018 Jeep Grand Cherokee Trackhawk

Ranked from 685 NHTSA owner complaints filed for this vehicle.

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1
Blown head gasket admitting coolant/combustion gas into the intake path
Medium severity
Several owners report head-gasket failures with coolant burning/leaking into cylinders, which can upset intake-side sensor readings and fuel trim.
Reported in 3 NHTSA complaints
Parts:head gasket
2
Intake vacuum leak from a cracked EGR cooler/valve assembly
Medium severity
Owners report a cracked EGR cooler and a failed EGR valve/intake manifold with heavy carbon buildup, either of which can leak unmetered air into the intake tract.
Reported in 2 NHTSA complaints
Parts:EGR cooler EGR valve
3
Weak or failing high-pressure fuel pump
High severity
An owner reports a slow-crank/hard-start pattern and cites widespread reports of high-pressure fuel pump issues on this platform; a pump that can't maintain rail pressure under load leans the mixture.
Reported in 1 NHTSA complaint
Parts:fuel pump
4
Dirty or failing MAF sensor
Medium severity
A contaminated or drifting MAF sensor under-reports incoming air, causing the PCM to under-fuel.
Common cause
Parts:mass airflow sensor
5
Stuck-open PCV valve
Low severity
Excess crankcase air pulled past a stuck PCV valve leans the idle mixture.
Common cause
Parts:PCV valve
6
Intake manifold gasket leak
Medium severity
A leaking manifold gasket admits unmetered air downstream of the MAF sensor, producing a persistent lean trim.
Common cause
Parts:intake manifold 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