P0171 on a 2021 Honda Cr V Hybrid

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 2021 Honda Cr V Hybrid

Ranked from 410 NHTSA owner complaints filed for this vehicle.

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1
Failed or clogged fuel injector(s)
Medium severity
Fuel injector replacement (including full injector kits) was repeatedly performed on this model in response to check-engine/lean-running complaints.
Reported in 4 NHTSA complaints
Parts:fuel injector
2
Failing high-pressure fuel pump
High severity
Dealer diagnostics on this vehicle directly identified a failed high-pressure fuel pump as the cause of sudden power loss/lean-running events.
Reported in 2 NHTSA complaints
Parts:fuel pump
3
Intake manifold air leak
Medium severity
One vehicle's intake manifold was found to have come loose/failed and required reseating, which would draw unmetered air and lean the mixture.
Reported in 1 NHTSA complaint
Parts:intake manifold gasket
4
Vacuum/intake leak (hoses, gaskets, PCV lines)
Medium severity
Unmetered air entering downstream of the MAF sensor is the single most common cause of a lean-bank code.
Common cause
5
Dirty or failing mass air flow (MAF) sensor
Medium severity
A MAF under-reporting actual airflow causes the ECU to under-fuel, producing a lean trim code.
Common cause
Parts:mass air flow sensor
6
Exhaust leak upstream of the front oxygen sensor
Low severity
A leak ahead of the sensor draws in outside air that the sensor reads as excess oxygen, mimicking a lean condition.
Common cause
7
Stuck-open PCV valve
Low severity
A PCV valve stuck open admits excess unmetered air into the intake, leaning the mixture.
Common cause
Parts:PCV valve

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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