Worn spark plugs or failing ignition coils (often more than one). A vacuum leak, which leans out the mixture across several cylinders. Low fuel pressure: a weak fuel pump or clogged fuel filter. A dirty or failing mass airflow (MAF) sensor. Bad gas or water in the fuel. Low compression from worn rings, valves or a head gasket (less common).

Trouble codes › P0300

P0300 Random/Multiple Cylinder Misfire Detected

Q: What does P0300 mean?

P0300 means the engine is misfiring in more than one cylinder, often from worn plugs or coils, a vacuum leak or low fuel pressure. The engine computer watches how smoothly the crankshaft turns. When a cylinder doesn't fire, the crankshaft slows for a moment. P0300 means it's seeing misfires in more than one cylinder, or moving around between cylinders, rather than in one cylinder.

Ignition and misfire

P0300 means the engine is misfiring in more than one cylinder, often from worn plugs or coils, a vacuum leak or low fuel pressure.

The engine computer watches how smoothly the crankshaft turns. When a cylinder doesn't fire, the crankshaft slows for a moment. P0300 means it's seeing misfires in more than one cylinder, or moving around between cylinders, rather than in one cylinder.

Can I keep driving? Not if you can avoid it.

If the check-engine light is flashing, ease off and stop driving as soon as you safely can: a heavy misfire dumps unburned fuel into the catalytic converter and can overheat and destroy it. A steady light with a mild misfire is less urgent, but get it checked soon.

Common causes

Worn spark plugs or failing ignition coils (often more than one)
A vacuum leak, which leans out the mixture across several cylinders
Low fuel pressure: a weak fuel pump or clogged fuel filter
A dirty or failing mass airflow (MAF) sensor
Bad gas or water in the fuel
Low compression from worn rings, valves or a head gasket (less common)

Symptoms

Rough idle, shaking or stumbling
Hesitation or loss of power when accelerating
Flashing or steady check-engine light
Worse fuel economy, sometimes a fuel smell from the exhaust

Common on: Ford F-150, Chevrolet Silverado 1500, Toyota Camry, Honda Civic, Honda Accord, Honda CR-V, Toyota RAV4, Toyota Corolla, Toyota Tacoma, Ram 1500, Nissan Altima, Chevrolet Equinox, Jeep Grand Cherokee, Ford Escape, Ford Explorer, GMC Sierra 1500, Jeep Wrangler, Toyota Highlander, Chevrolet Malibu, Honda Odyssey, Hyundai Elantra, Ford Fusion, Chevrolet Tahoe, Dodge Grand Caravan, Chevrolet Traverse, GMC Acadia, Chevrolet Suburban, GMC Yukon, Ford Expedition, Honda Pilot, Dodge Durango

Known problems: GM 2.4L Ecotec oil consumption and timing chain wear · GM V8 AFM/DFM lifter failure · 5.7L Hemi lifter and camshaft wear ("Hemi tick") · Ford 3.5L EcoBoost intercooler condensation misfire · Honda 3.5L V6 VCM misfires and fouled spark plugs · Ford 1.5L and 1.6L EcoBoost coolant loss, overheating and misfires

What to check first

Note when it happens: cold start, idle, under load, in the rain. That narrows it down.
Check for other codes: lean codes (P0171, P0174) point to vacuum leaks or fuel delivery; single-cylinder codes (P0301-P0308) point to that cylinder.
Check the spark plugs' age and condition; replace them if they're past the maintenance interval.
Listen for hissing at idle and check vacuum hoses and the intake boot for cracks.
With a scan tool, look at misfire counts per cylinder and at fuel trims. High positive trims at idle that drop at higher rpm suggest a vacuum leak.
If plugs, coils and leaks check out, test fuel pressure and compression.

What does P0300 mean on your vehicle?

The likely cause depends on your engine. iRepair researches your exact year, make, model and engine (service bulletins, recalls and owner reports) and tells you what to check first. Your first 3 questions are free.

Ask iRepair about P0300

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Related codes

General guidance for P0300 on most vehicles. Some makers use the same code a little differently; confirm in the service information for your vehicle, put safety first, and see a professional when in doubt.