P0300 on a 2010 Dodge Grand Caravan

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 2010 Dodge Grand Caravan

Ranked from 1,038 NHTSA owner complaints filed for this vehicle.

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1
Ignition coil or spark plug failure causing cylinder-specific misfire
Medium severity
A dealer diagnosis in this batch pinpointed a #5 cylinder misfire under warranty, consistent with a single failed coil-on-plug or fouled plug on these 3.3L/3.8L/4.0L minivan engines.
Reported in 1 NHTSA complaint
Parts:ignition coil spark plug
2
Head gasket failure allowing coolant/compression loss into a cylinder
High severity
A reported cylinder head gasket failure would let coolant intrude into the combustion chamber or drop compression on that cylinder, producing a persistent misfire.
Reported in 1 NHTSA complaint
Parts:head gasket
3
Worn spark plugs
Low severity
Eroded or fouled plugs increase the firing voltage required and are a leading generic cause of random/multiple-cylinder misfire on higher-mileage vehicles.
Common cause
Parts:spark plug
4
Clogged or leaking fuel injector
Medium severity
An injector delivering too little or too much fuel produces a repeatable, cylinder-specific misfire.
Common cause
Parts:fuel injector
5
Vacuum leak
Medium severity
Unmetered air entering the intake leans one or more cylinders enough to misfire, especially at idle.
Common cause
Parts:vacuum hose
6
Low compression from worn piston rings or valves
High severity
Mechanical wear reduces a cylinder's ability to build compression, causing a weak or incomplete burn that registers as a misfire.
Common cause
7
EGR valve fault
Low severity
A stuck-open EGR valve over-dilutes the intake charge, which can produce a rough idle/misfire condition.
Common cause
Parts:EGR valve

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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