P0300 Random/Multiple Cylinder Misfire Detected
P0300 is a generic OBD2 powertrain code. It means “Random/Multiple Cylinder Misfire Detected” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker.
Ask the AI about P0300 on your car- System
- Powertrain (P)
- Code type
- Generic (SAE)
- Range
- P03xx
- Urgency
- High
What P0300 means
The engine computer watches the crankshaft speed up with every firing stroke. When it counts too many strokes that don’t deliver — misfires — spread across several cylinders, or ones it can’t pin to a single cylinder, it stores P0300.
Symptoms
- Shaking or a rough idle
- Jerking or stumbling under acceleration
- Loss of power
- A flashing check engine lamp when the misfire is severe
- A smell of fuel from the exhaust
Most likely causes
- Worn spark plugs or failing ignition coils or plug wires
- A lean mixture from a vacuum leak or low fuel pressure (often alongside P0171/P0174)
- Dirty or failing injectors
- An EGR valve stuck open
- Low compression or incorrect cam timing (look for camshaft or crankshaft correlation codes)
- Poor-quality or contaminated fuel
What to check first
- Note every other code stored with it — a lean or timing code tells you where to look first
- Check how old the spark plugs are and the condition of the coils and plug wires
- Look for vacuum leaks
- If the misfire persists with good ignition and fuel, have a compression test done
Can I keep driving with P0300?
Limit driving — get it checked promptly
Only gently, and only as far as the workshop. If the lamp flashes, stop as soon as it’s safe: unburnt fuel is burning inside the catalytic converter and can destroy it within miles.
What the wording tells you
A misfire code is set when the engine computer sees the crankshaft fail to speed up on a cylinder’s firing stroke often enough to raise emissions or threaten the catalytic converter. It names the symptom, not the cause — spark, fuel and compression are the three places to look.
How P0300 breaks down
Powertrain. Engine, transmission, fuel and emissions — the codes behind the check engine lamp.
Generic code: defined by SAE, the same on every make.
Ignition system & misfire.
The specific fault within this range.
Where to look: Ignition system & misfire
Misfire detection, ignition coils, crankshaft and camshaft position sensors and knock sensors. The engine computer detects misfires from dips in crankshaft speed, so this area often reports a problem that starts elsewhere — in the fuel supply or in compression.
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Frequently asked
What does P0300 mean?
P0300 is a generic OBD2 powertrain code. It means “Random/Multiple Cylinder Misfire Detected” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker. The engine computer watches the crankshaft speed up with every firing stroke. When it counts too many strokes that don’t deliver — misfires — spread across several cylinders, or ones it can’t pin to a single cylinder, it stores P0300.
Can I drive with P0300?
Only gently, and only as far as the workshop. If the lamp flashes, stop as soon as it’s safe: unburnt fuel is burning inside the catalytic converter and can destroy it within miles.
What causes P0300?
Worn spark plugs or failing ignition coils or plug wires; A lean mixture from a vacuum leak or low fuel pressure (often alongside P0171/P0174); Dirty or failing injectors; An EGR valve stuck open; Low compression or incorrect cam timing (look for camshaft or crankshaft correlation codes); Poor-quality or contaminated fuel.
How do I clear P0300?
Fix the cause first, then clear it with any OBD2 scanner or app. Once the fault is gone the car also clears it on its own: the check engine lamp goes off after the self-test passes on three drive cycles in a row, and the stored code ages out after about 40 warm-ups. Clearing without a repair only hides it for a while — and resets the readiness monitors an emissions inspection looks at.
Is P0300 the same on every car?
Yes. P0300 is a generic SAE J2012 code, so its definition is identical on every make and model. What differs is the cause behind it and the repair procedure, which depend on the engine — that’s why the assistant on this page asks for your car.
Guides
Definitions: the generic SAE J2012 codes from Brimly’s offline dictionary (data version 2026.09). Causes and advice are general guidance for all makes — the service information for your car has the last word.