P0300 on a 2019 Honda Civic Hatch Type R

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 Civic Hatch Type R

Ranked from 420 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Fuel pump impeller failure (open recall 23V-858) causing fuel starvation
High severity
A large number of owners report the recalled fuel pump module failing or awaiting replacement, causing stalling and rough running from inadequate fuel delivery.
Reported in 5 NHTSA complaints
Parts:fuel pump
2
Ignition coil failure from hood-scoop water intrusion (known FK8 design flaw)
High severity
Owners describe water entering through the hood scoop and dripping onto the #4 cylinder coil, rusting the coil/plug and throwing a check-engine light; a mechanic's ignition-coil-and-plug swap was also reported for a jerk/shudder misfire.
Reported in 3 NHTSA complaints
Parts:ignition coil spark plug
3
Head gasket failure flooding cylinders with coolant
High severity
Multiple owners report a low-mileage head gasket design flaw that lets coolant reach the cylinders (one explicitly describes cylinders "flooded with coolant"), causing sudden misfire/stall and loss of all assist systems.
Reported in 3 NHTSA complaints
Parts:head gasket
4
Fuel injector leak / fuel dilution of engine oil
Medium severity
Owners report gasoline mixing into the engine oil badly enough to smell fuel and lose power on the highway -- consistent with a leaking/over-fueling injector on this direct-injection engine.
Reported in 2 NHTSA complaints
Parts:fuel injector
5
Worn spark plugs
Low severity
Plugs out of gap or fouled with carbon misfire under load; inspect and replace per service interval.
Common cause
Parts:spark plugs
6
Vacuum or intake leak
Medium severity
Unmetered air entering after the MAF causes a lean misfire, most noticeable at idle.
Common cause
7
Carbon-fouled intake valves
Low severity
Direct-injection engines build up carbon on intake valves over time, disrupting airflow/atomization and causing misfire.
Common cause
8
Low compression (worn rings/valves)
High severity
Compression loss on one or more cylinders from wear or valve damage causes a persistent misfire on that cylinder.
Common cause
9
EGR valve fault
Low severity
A stuck-open EGR valve over-dilutes the intake charge at idle, producing a rough idle/misfire.
Common cause
Parts:EGR valve

Part links go to Amazon search results for this vehicle. As an Amazon Associate, WrenchConnect earns from qualifying purchases — always confirm fitment for your exact trim and engine before ordering.

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.

Rather have a pro handle it? Find a vetted local mechanic.

Matching symptoms

Car Runs Rough Flashing Check Engine Light