P0300 on a 2019 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 2019 Honda Cr V
Ranked from 1,063 NHTSA owner complaints filed for this vehicle.
- 1
Faulty Fuel Injectors
High severityFuel injectors leak or fail, causing a rich condition (P0172), misfires (P0300/P0301/P0302), and fuel dilution in the oil. Confirmed by failed A/F tests, fuel in oil, and multiple warning lights illuminating.
Reported in 9 NHTSA complaints - 2
Blown Head Gasket
High severityCoolant leaks into the combustion chamber causing misfires, rough running on cold starts, and overheating. Confirmed by compression tests, coolant loss, and visual inspection of the gasket.
Reported in 7 NHTSA complaints - 3
Fuel Dilution in Engine Oil
High severityGasoline mixes with engine oil (often due to leaking injectors), reducing lubrication and causing internal engine damage, sludge, or turbo failure. Confirmed by oil analysis or smelling fuel on the dipstick.
Reported in 4 NHTSA complaints - 4
Turbocharger Failure
High severityTurbocharger fails, often secondary to oil dilution/sludge, causing a sudden loss of power and misfires. Confirmed by inspecting the turbo for damage or excessive play.
Reported in 4 NHTSA complaints - 5
Failing Fuel Pump
Medium severityA defective fuel pump can cause hesitation, stalling, and misfires due to inadequate fuel pressure. Confirmed by checking fuel pressure and referencing the known fuel pump recall.
Reported in 2 NHTSA complaints - 6
Low Engine Compression
High severityInternal engine wear (like sticking piston rings) or damage prevents proper combustion, leading to misfires. Confirmed by performing a cylinder compression or leak-down test.
Reported in 1 NHTSA complaint - 7
Worn Spark Plugs / Ignition Coils
Low severityStandard wear or fouling (sometimes secondary to rich conditions or coolant leaks) causes weak spark and misfires. Confirmed by inspecting plugs for fouling and testing coil output.
Common cause - 8
Vacuum Leak
Low severityUnmetered air enters the intake manifold, causing a lean condition and random misfires. Confirmed by smoke testing the intake system and checking fuel trims.
Common cause
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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