P0300 on a 2018 Jeep Renegade

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 Jeep Renegade

Ranked from 440 NHTSA owner complaints filed for this vehicle.

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1
Excessive oil consumption from worn piston rings/cylinder bores
High severity
An unusually large share of owners of this 2.4L engine report burning a quart of oil every 1,000 miles or less (subject of Chrysler Customer Satisfaction Notification W80), leading to low oil, engine stalling, and confirmed 'fatal internal wear' requiring engine replacement -- worn rings and low compression are a direct, well-established cause of misfire.
Reported in 15 NHTSA complaints
Parts:piston rings
2
Engine control module (ECM/PCM) fault
Low severity
One owner's stalling was traced to an ECM/PCM failure rather than a mechanical cause, which can produce misfire-like stalling symptoms.
Reported in 1 NHTSA complaint
3
Fouled or worn spark plugs
Medium severity
Oil being burned in the combustion chamber (per the documented consumption defect) commonly fouls spark plugs, a classic cause of random misfire.
Common cause
Parts:spark plugs
4
Failing ignition coils
Medium severity
Coil-on-plug failures are a common, independent cause of a cylinder-specific misfire on this engine family.
Common cause
Parts:ignition coil
5
Clogged or leaking fuel injectors
Medium severity
An injector delivering incorrect fuel volume to a cylinder produces a repeatable misfire.
Common cause
Parts:fuel injector
6
Vacuum/intake leak
Medium severity
Unmetered air entering after the MAF sensor causes lean misfire, typically worse at idle.
Common cause
7
Carbon-fouled intake valves
Low severity
Carbon buildup on the intake valves disrupts airflow and atomization, especially on direct-injection engines.
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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Matching symptoms

Car Runs Rough Flashing Check Engine Light