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P0171

P0171 on a 2016 Ram 1500

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 Ram 1500

Ranked from 1,508 NHTSA owner complaints filed for this vehicle.

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  1. 1

    Weak or failing fuel pump / HPFP (Recall Z46 repeat failures)

    High severity

    Several owners report the high-pressure fuel pump failing -- including cases where the recall's replacement pump failed again the same way -- which reduces fuel delivery and can pull the mixture lean under load.

    Reported in 4 NHTSA complaints
    Parts:fuel pump
  2. 2

    Intake manifold leak or defect (3.0L EcoDiesel)

    Medium severity

    One owner's dealer confirmed the intake manifold needed replacement for hesitation and a check engine light, consistent with an unmetered-air leak feeding a lean condition.

    Reported in 1 NHTSA complaint
    Parts:intake manifold
  3. 3

    Dirty or failing mass airflow (MAF) sensor

    Medium severity

    A contaminated or drifting MAF under-reports intake air, causing the ECM to under-fuel and trim lean.

    Common cause
    Parts:mass airflow sensor
  4. 4

    Clogged fuel filter

    Medium severity

    Restricted fuel flow to the engine under demand starves it of fuel relative to incoming air, a common lean-code cause.

    Common cause
    Parts:fuel filter
  5. 5

    PCV valve stuck open

    Low severity

    Excess unmetered crankcase air pulled through a stuck-open PCV valve skews the air/fuel ratio lean.

    Common cause
    Parts:PCV valve
  6. 6

    Exhaust leak upstream of the front oxygen sensor

    Medium severity

    A leak ahead of the sensor draws in outside air, making the ECM see a falsely lean exhaust reading.

    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

1

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.

2

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.

3

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.

4

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.

5

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