P0300 on a 2024 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 2024 Honda Cr V
Ranked from 370 NHTSA owner complaints filed for this vehicle.
- 1
Fuel injector failure (leaking/clogged/electrically faulty)
High severityRepeatedly diagnosed as the root cause across this batch — dealers replaced injectors after diagnosing cylinder-specific misfires (cyl 2, cyl 4) and one owner's entire injector set was condemned; described by Honda techs as a widespread 2024 CR-V Hybrid issue.
Reported in 6 NHTSA complaintsParts:fuel injector - 2
Head gasket failure with coolant intrusion into a cylinder
High severitySeveral owners had a catastrophic head-gasket failure that let coolant into the cylinders, causing rough running, misfire-like shaking, and sudden power loss.
Reported in 3 NHTSA complaintsParts:head gasket - 3
Coolant-fouled or corroded throttle body / EGR passage
Medium severityOwners had the throttle body replaced after coolant seepage or EGR-routed exhaust corroded the throttle butterfly, causing rough running and an emissions/power-reduction fault.
Reported in 2 NHTSA complaintsParts:throttle body - 4
Ignition coil and/or spark plug failure
Medium severityOne vehicle was diagnosed with a bad spark plug and bad ignition coil alongside faulty injectors when it threw misfire-pattern check-engine codes.
Reported in 1 NHTSA complaint - 5
- 6
Vacuum or intake air leak
Medium severityUnmetered air entering after the MAF sensor leans out individual cylinders enough to cause a rough idle or misfire; check hoses and intake gaskets with a smoke test.
Common cause - 7
Carbon-fouled intake valves
Low severityDirect-injection engines like this one are prone to carbon buildup on the valves, which can disrupt airflow/fuel atomization enough to trigger a random misfire.
Common cause - 8
Low cylinder compression (worn rings/valves)
Medium severityA compression test isolates a mechanical cause when spark and fuel components test fine.
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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