P0300 on a 2023 Honda Cr V
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 2023 Honda Cr V
Ranked from 506 NHTSA owner complaints filed for this vehicle.
- 1
Head gasket failure allowing coolant into a cylinder
High severityMultiple 2023 CR-V owners (mostly Hybrid) report a blown or failing head gasket letting coolant into a cylinder, fouling combustion and setting a misfire code before requiring an engine replacement or rebuild.
Reported in 6 NHTSA complaintsParts:head gasket - 2
Piston or connecting-rod failure causing loss of compression
High severityTwo owners describe a broken piston rod or a misfiring cylinder severe enough to shake the engine block, both requiring a replacement engine.
Reported in 2 NHTSA complaints - 3
Worn or fouled spark plugs
Medium severityA dealer replaced spark plugs on this exact vehicle to resolve a startup misfire; worn plugs are the single most common P0300 cause across all vehicles.
Reported in 1 NHTSA complaintParts:spark plugs - 4
Failing or clogged fuel injector
Medium severityOne owner's dealer suspected a bad fuel injector after a highway power loss with a misfiring cylinder, citing a parts shortage for the replacement.
Reported in 1 NHTSA complaintParts:fuel injector - 5
Failing ignition coil
Medium severityA weak or dead coil-on-plug drops spark to one or more cylinders, producing an intermittent or steady misfire; check for stored coil codes alongside P0300.
Common causeParts:ignition coil - 6
Vacuum or intake air leak
Medium severityUnmetered air entering after the MAF sensor leans out the mixture enough to cause a rough idle and random misfire.
Common cause - 7
Carbon-fouled intake valves
Low severityDirect-injection engines like this one don't wash the intake valves with fuel, letting carbon build up and disrupt airflow/combustion until cleaned.
Common cause - 8
EGR valve stuck open or clogged
Low severityExcess or blocked exhaust gas recirculation upsets the air-fuel charge at idle and low load, contributing to a random misfire.
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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