P0300 on a 2013 Jeep Wrangler

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 2013 Jeep Wrangler

Ranked from 647 NHTSA owner complaints filed for this vehicle.

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1
Defective Cylinder Head / Valve / Spring (Left Bank)
High severity
A known issue on the 3.6L Pentastar engine involves premature wear or failure of the left cylinder head, valves, or springs, leading to low compression and misfires. This is confirmed by a compression leak test and is referenced in TSB 09-002-14 (Extended Warranty X56).
Reported in 4 NHTSA complaints
2
Worn / Failed Rocker Arms and Lifters
High severity
The 3.6L engine is notorious for rocker arm bearing failure, causing a loud ticking noise and eventual misfires or camshaft damage. It is confirmed by removing the valve cover and inspecting the rocker arms for play or damage.
Reported in 2 NHTSA complaints
3
Faulty Spark Plugs
Low severity
Worn or fouled spark plugs are a standard cause of random/multiple misfires. Confirmed by inspecting the spark plug electrodes for wear, carbon buildup, or improper gap.
Common cause
4
Faulty Ignition Coils
Medium severity
A failing ignition coil can cause intermittent or consistent misfires. Confirmed by testing coil resistance or moving the coil to another cylinder to see if the misfire follows.
Common cause
5
Vacuum Leak
Medium severity
Unmetered air entering the intake manifold can lean out the air/fuel mixture, causing random misfires across multiple cylinders. Confirmed by a smoke test or listening for hissing noises near the intake.
Common cause
6
Fuel Delivery Issues (Low Fuel Pressure / Failing Injectors)
Medium severity
Inadequate fuel pressure or clogged fuel injectors can starve the engine of fuel, leading to random misfires. Confirmed by checking fuel pressure with a gauge or testing injector pulse and flow.
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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Matching symptoms

Car Runs Rough Flashing Check Engine Light