Faulty spark plugs or plug wires. Faulty ignition coil(s). Lean condition: vacuum leak or unmetered air past the MAF sensor. EGR valve stuck open, blocked or leaking. Faulty fuel injector(s). Faulty oxygen sensor(s). Faulty camshaft position sensor. Burned exhaust valve. Faulty catalytic converter. Defective engine computer (rare). Incorrect ignition timing, low or weak fuel pressure, a defective MAF, throttle position or crankshaft sensor, or mechanical problems such as low compression, a leaking head gasket or valve problems (listed by RepairPal).

Replace worn spark plugs, wires, coil packs. Repair vacuum leaks. Repair or replace a stuck EGR valve. Replace faulty injectors. Replace a damaged catalytic converter (a rotten-egg smell from the exhaust can point to a bad converter, per OBD-Codes.com).

P0300⚡ Ignition / misfireStop and fix promptly

P0300: Random/Multiple Cylinder Misfire Detected (Meaning, Causes, Fixes)

Q: What does P0300 mean?

P0300 means the engine computer has detected misfires that aren't limited to one cylinder, or that move between cylinders. It doesn't say which cylinder or why. Start with spark plugs, coils and wiring, then look for vacuum leaks and fuel problems. The PCM has detected that not all cylinders are firing properly. P0300 means random or multiple misfire. If the last digit is not zero it names the cylinder: P0302 is cylinder 2. P0300 by itself doesn't tell you which cylinders are misfiring or why. According to OBD-Codes.com, random misfires that jump between cylinders are often caused by a lean condition, such as a vacuum leak, unmetered air getting past the airflow sensor, or an EGR valve stuck open.

Q: Can I keep driving with P0300?

Stop and fix promptly. Take it seriously. If the check engine light is flashing, that indicates a severe misfire: reduce speed and stop driving soon, because severe misfire can quickly damage the catalytic converter. Even with a steady light, get it diagnosed promptly. RepairPal also rates P0300 'Urgent'.

Reviewed 2026-10-21 · Based on 4 cited source(s)

What P0300 means

The PCM has detected that not all cylinders are firing properly. P0300 means random or multiple misfire. If the last digit is not zero it names the cylinder: P0302 is cylinder 2. P0300 by itself doesn't tell you which cylinders are misfiring or why. According to OBD-Codes.com, random misfires that jump between cylinders are often caused by a lean condition, such as a vacuum leak, unmetered air getting past the airflow sensor, or an EGR valve stuck open.

Severity: can I keep driving?

Stop and fix promptly

Take it seriously. If the check engine light is flashing, that indicates a severe misfire: reduce speed and stop driving soon, because severe misfire can quickly damage the catalytic converter. Even with a steady light, get it diagnosed promptly. RepairPal also rates P0300 'Urgent'.

Common symptoms

Check engine light on or flashing
Engine harder to start
Stumbling, rough running or hesitation

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

Faulty spark plugs or plug wires
Faulty ignition coil(s)
Lean condition: vacuum leak or unmetered air past the MAF sensor
EGR valve stuck open, blocked or leaking
Faulty fuel injector(s)
Faulty oxygen sensor(s)
Faulty camshaft position sensor
Burned exhaust valve
Faulty catalytic converter
Defective engine computer (rare)
Incorrect ignition timing, low or weak fuel pressure, a defective MAF, throttle position or crankshaft sensor, or mechanical problems such as low compression, a leaking head gasket or valve problems (listed by RepairPal)

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

If the light is flashing, drive gently and stop soon. Don't keep driving hard.
Read all codes. Cylinder-specific codes (P0301–P0308) tell you where to look.
Check wiring and connectors to the coils and spark plugs.
Inspect the spark plugs and, if fitted, plug wires, distributor cap and rotor. Replace them if they're due by the maintenance schedule.
Check the coils. On coil-on-plug engines, swapping a coil to another cylinder and seeing if the misfire moves is a common test.
Listen and look for vacuum leaks (hissing, cracked hoses). Check for lean codes like P0171/P0174.
If the engine is running fine with no symptoms, OBD-Codes.com suggests clearing the code and seeing if it returns.

Typical fixes

Replace worn spark plugs, wires, coil packs
Repair vacuum leaks
Repair or replace a stuck EGR valve
Replace faulty injectors
Replace a damaged catalytic converter (a rotten-egg smell from the exhaust can point to a bad converter, per OBD-Codes.com)

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

The light is flashing and the engine shakes badly: consider towing
Ignition parts are new and the misfire persists (compression or valve problems need tools)
Fuel injector or camshaft sensor diagnosis needs an advanced scan tool and the factory service manual

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Can I drive with P0300?

With a flashing light, only as far as you need to stop safely. Severe misfire can damage the catalytic converter in a short time.

Why doesn't P0300 tell me which cylinder?

It's the random/multiple misfire code. A scan tool with misfire counters, or extra P030x codes, can narrow it down.

Sources

Last reviewed 2026-10-21. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.