P0171 on a 2019 Chevrolet Traverse

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 Chevrolet Traverse

Ranked from 399 NHTSA owner complaints filed for this vehicle.

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1
Exhaust bracket/manifold leak upstream of the O2 sensor
Medium severity
An unusually large cluster of owners report a broken exhaust bracket cracking the exhaust pipe or catalytic converter joint, admitting outside air ahead of the sensor and skewing the fuel-trim reading.
Reported in 8 NHTSA complaints
Parts:exhaust bracket exhaust pipe exhaust manifold gasket
2
EVAP purge valve stuck open / repeatedly failing
Medium severity
Several owners had a canister purge valve diagnosed as not closing completely or throwing high-purge-flow codes, and the failure recurred even after replacement -- a stuck-open purge path acts like a vacuum leak on fuel trim.
Reported in 4 NHTSA complaints
Parts:purge valve EVAP charcoal canister
3
Vacuum or intake air leak
Medium severity
A cracked hose or loose intake boot admits unmetered air; smoke-test the intake tract.
Common cause
4
Dirty or failing mass airflow (MAF) sensor
Low severity
A contaminated or drifting MAF under-reports intake air, causing the fuel system to under-fuel; clean or test the sensor.
Common cause
Parts:mass airflow sensor
5
Intake manifold gasket failure
Medium severity
A leaking intake gasket introduces unmetered air directly into the manifold.
Common cause
Parts:intake manifold gasket
6
Weak fuel pump or clogged fuel filter
Medium severity
Reduced fuel delivery under load produces the same lean-code symptoms as an air leak; check fuel pressure under load.
Common cause
Parts:fuel pump fuel filter

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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