P0171 on a 2017 Jeep Grand Cherokee

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 2017 Jeep Grand Cherokee

Ranked from 361 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Low Fuel Pressure (Failing Fuel Pump or Clogged Filter)
High severity
Insufficient fuel delivery creates a lean condition. Confirmed by testing fuel pressure with a mechanical gauge and finding it below specification under load.
Reported in 1 NHTSA complaint
2
Vacuum Leaks (Intake Manifold Gaskets, Vacuum Hoses, PCV System)
Medium severity
Unmetered air entering the engine leans out the air/fuel mixture. Look for cracked hoses, hissing sounds, or high positive fuel trims at idle that improve at higher RPMs.
Common cause
3
Faulty Oxygen (O2) Sensor (Upstream)
Medium severity
A degraded or failing upstream O2 sensor can falsely report a lean condition, causing the PCM to set P0171. Confirmed by sluggish sensor response or skewed voltage readings on a scan tool.
Common cause
4
Dirty or Faulty Mass Air Flow (MAF) Sensor / MAP Sensor
Medium severity
An inaccurate reading of incoming air volume/pressure causes the PCM to under-fuel the engine. Confirmed by cleaning the sensor or checking g/s readings against expected values.
Common cause
5
Clogged or Dirty Fuel Injectors
Medium severity
Restricted injectors fail to spray the commanded amount of fuel, leading to a lean mixture. Confirmed by injector balance testing or observing localized misfires.
Common cause
6
Exhaust Leaks (Before the Upstream O2 Sensor)
Medium severity
Air entering the exhaust stream before the O2 sensor tricks it into reading lean. Look for soot marks, ticking noises, or cracked exhaust manifolds.
Common cause

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