P0300 on a 2018 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 2018 Honda Pilot
Ranked from 427 NHTSA owner complaints filed for this vehicle.
- 1
Connecting rod bearing wear/failure (J35 V6 — NHTSA investigation PE25008)
High severityA large cluster of complaints describe engine knocking that progressed to stalling or complete engine failure, explicitly diagnosed by shops/dealers as connecting rod bearing failure, matching an open NHTSA investigation into this engine.
Reported in 11 NHTSA complaints - 2
Camshaft position sensor failure (P0369)
Medium severityOwners had a camshaft position sensor replaced after a P0369 code, with one noting excess camshaft play as the underlying cause of repeat sensor failure.
Reported in 2 NHTSA complaintsParts:camshaft position sensor - 3
Fuel injector fouling/contamination
Medium severityOne owner linked a delayed fuel-pump repair to resulting fuel injector contamination and rough running.
Reported in 1 NHTSA complaintParts:fuel injectors - 4
Timing belt/tensioner wear
Medium severityA ticking timing belt tensioner reported by one owner can allow belt slap/timing drift that disrupts combustion.
Reported in 1 NHTSA complaint - 5
Worn spark plugs
Low severityStandard misfire cause; inspect gap/fouling and replace per interval.
Common causeParts:spark plugs - 6
Failing ignition coils
Medium severityA weak coil drops spark energy to one cylinder; swap-test to isolate.
Common causeParts:ignition coils - 7
Vacuum or intake leaks
Medium severityUnmetered air causes lean misfire, most noticeable at idle.
Common cause
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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
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.
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.
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.
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.
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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