P0171 on a 2016 Chevrolet Colorado

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 2016 Chevrolet Colorado

Ranked from 695 NHTSA owner complaints filed for this vehicle.

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1
Faulty canister purge solenoid stuck open
Medium severity
A dealer diagnosed a faulty purge solenoid on a truck that cranked-but-wouldn't-start after fueling and idled roughly, citing GM Special Coverage Adjustment Letter #18029 for this known problem on the platform; an open purge path leans out idle/cruise fueling.
Reported in 2 NHTSA complaints
Parts:purge valve
2
Dry-rotted/cracked high-pressure fuel pump line
High severity
One owner documented visible cracking and pressure loss in the high-pressure fuel line/pump on this exact model, noting GM has an (unapplied-to-their-VIN) recall for the same defect on 2016-2018 Colorados -- reduced delivery pressure directly produces a lean code.
Reported in 1 NHTSA complaint
Parts:fuel pump fuel line
3
Failing mass air flow (MAF) sensor
Medium severity
Diagnosed together with the purge valve on a truck that shuddered and lost power on an incline; an under-reporting MAF causes the PCM to under-fuel.
Reported in 1 NHTSA complaint
Parts:mass airflow sensor
4
Vacuum or intake leak
Medium severity
A cracked intake boot or hose lets unmetered air in, most noticeable at idle and light throttle.
Common cause
Parts:intake boot
5
Stuck-open PCV valve
Low severity
A PCV valve stuck open pulls unmetered air into the intake, biasing fuel trims lean.
Common cause
Parts:PCV valve
6
Exhaust leak upstream of the O2 sensor
Low severity
Outside air drawn in through a manifold/gasket leak skews the upstream O2 reading lean.
Common cause
7
Intake manifold gasket leak
Medium severity
A failed gasket admits unmetered air downstream of the throttle body, biasing fuel trims lean.
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