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P0300

P0300 on a 2016 Honda Pilot

P0300 is a generic OBD2 powertrain code for random or multiple cylinder misfire. Unlike P0301 through P0308, it does not point to one specific cylinder, so the cause can be ignition, fuel, air, sensor, or mechanical.

Not your vehicle? See general P0300 info.

Most common causes on the 2016 Honda Pilot

Ranked from 1,672 NHTSA owner complaints filed for this vehicle.

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  1. 1

    Connecting rod bearing failure (rod knock)

    High severity

    Overwhelming pattern in this vehicle's complaints: premature rod bearing wear (subject of NHTSA recall 23V-751) causes knocking, rough running, and eventual catastrophic engine failure that begins as misfire-like symptoms.

    Reported in 21 NHTSA complaints
  2. 2

    Failing fuel injectors (Honda TSB 20-100)

    Medium severity

    One owner's injectors for cylinders #4/#5 were replaced after a rich/lean cylinder imbalance was diagnosed; Honda's TSB covers debris-related injector defects on this 3.5L V6.

    Reported in 1 NHTSA complaint
    Parts:fuel injector
  3. 3

    Low fuel rail pressure / weak fuel pump (P0087)

    Medium severity

    One owner had repeated P0087 low fuel-pressure codes and stalling, initially misdiagnosed with an injector swap before a failing in-tank fuel pump was identified — pressure-starved cylinders will misfire.

    Reported in 1 NHTSA complaint
    Parts:fuel pump
  4. 4

    Worn spark plugs

    Low severity

    Eroded electrodes widen the spark gap and cause intermittent misfire, especially under load; inspect gap and electrode wear at the recommended interval.

    Common cause
    Parts:spark plug
  5. 5

    Failing ignition coil(s)

    Medium severity

    A weakening coil misfires under load or when hot; swap-test coils cylinder-to-cylinder to isolate.

    Common cause
    Parts:ignition coil
  6. 6

    Vacuum/intake leak

    Medium severity

    Unmetered air leans out one or more cylinders enough to misfire; check intake boots, PCV lines, and manifold gaskets with a smoke test.

    Common cause
  7. 7

    Carbon-fouled intake valves

    Low severity

    Direct-injection V6 engines build carbon on the backs of intake valves over time, disrupting airflow/fuel atomization and causing rough idle or misfire.

    Common cause
  8. 8

    EGR valve/passage fault

    Low severity

    A stuck-open EGR valve dilutes the intake charge excessively and can cause misfire at idle or light throttle; check for carbon-clogged passages.

    Common cause
    Parts:EGR valve

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These causes are aggregated from NHTSA owner complaints and general repair knowledge — this is not a diagnosis. P0300 on your car still needs shop confirmation before any repair.

Common symptoms

  • Flashing or steady check engine light
  • Rough idle
  • Shaking under acceleration
  • Loss of power
  • Fuel smell from exhaust

What to check before replacing parts

1

Scan for cylinder-specific misfire codes

Look for: A companion P0301–P0308 pins the misfire to one cylinder — start there. P0300 with no cylinder code points at something hitting several at once: fuel pressure, a large vacuum leak, or timing.

2

Inspect the spark plugs and coils

Look for: Pull the plugs: black/sooty = rich, oily = oil intrusion, white/blistered = lean or overheating, cracked porcelain or an out-of-spec gap = replace. Then swap a coil to another cylinder — if a cylinder-specific code follows the coil, the coil is bad.

3

Check fuel trims for a vacuum leak

Look for: High positive short- and long-term trims (worst at idle, improving as RPM rises) mean unmetered air is getting in. Smoke-test the intake and listen for hissing.

4

Verify fuel pressure

Look for: Compare running/cranking pressure to the vehicle spec. Low or dropping pressure starves multiple cylinders and reads as a random misfire — suspect the pump, filter, or regulator.

5

Compression / leak-down test if ignition and fuel check out

Look for: A cylinder 15%+ below the others, or leak-down hissing from the intake (intake valve), exhaust (exhaust valve), or oil filler (rings), means the misfire is mechanical — not a swap-in part.

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Matching symptoms

Car Runs RoughFlashing Check Engine Light