P0171 on a 2016 Honda Cr V

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 Honda Cr V

Ranked from 388 NHTSA owner complaints filed for this vehicle.

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1
Failing high-pressure fuel pump (low fuel rail pressure)
High severity
A wave of CR-V owners had their HP fuel pump replaced after stalling, power loss, and a scanned low-fuel-rail-pressure code; a related recall covers 2017-2020 models but many 2016 pumps fail the same way.
Reported in 9 NHTSA complaints
Parts:high-pressure fuel pump
2
Fuel line or fitting leak reducing fuel pressure
High severity
One owner had a fuel line on top of the tank spilling fuel, which drops rail pressure and can bias the mixture lean.
Reported in 1 NHTSA complaint
Parts:fuel line
3
Vacuum or intake air leak
Medium severity
Cracked intake boots, PCV, or brake-booster hoses let in unmetered air; listen for a hiss and smoke-test the intake.
Common cause
4
Dirty or failing MAF sensor
Medium severity
A contaminated or drifting MAF sensor under-reports airflow, causing the PCM to add insufficient fuel.
Common cause
Parts:mass airflow sensor
5
Stuck-open PCV valve
Low severity
An open PCV valve pulls extra air into the intake at idle, leaning the mixture.
Common cause
Parts:PCV valve
6
Intake manifold gasket leak
Medium severity
A leaking manifold gasket admits unmetered air, most noticeable at idle.
Common cause
Parts:intake manifold gasket
7
Exhaust leak ahead of the upstream O2 sensor
Low severity
A leak before the front sensor draws in outside air and skews the reading lean.
Common cause

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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