P0300
Random/Multiple Cylinder Misfire Detected
Your engine's computer has detected that one or more cylinders are not firing correctly, but it can't pinpoint a specific cylinder, or multiple cylinders are misfiring randomly.
The powertrain control module (PCM) has detected that multiple cylinders are misfiring or that the misfire is not specific to a single cylinder.
Common causes
- high
Vacuum Leaks
Leaks in vacuum lines, intake manifold gaskets, or PCV system can cause unmetered air to enter, leading to a lean condition and misfires across multiple cylinders.
Typical part cost: $50-300
- high
Faulty Spark Plugs, Ignition Coils, or Wires
Worn spark plugs, failing ignition coils, or damaged spark plug wires can lead to inconsistent or absent spark, causing misfires.
Typical part cost: $100-600+
See all causes + fix costs
Create a free Wrenchify account to unlock the rest for P0300.
Unlock causesFree forever · No credit card
First things to check
- 1Check for other related codes (e.g., P0171/P0174 for lean conditions, specific cylinder misfires).
- 2Inspect spark plugs, ignition coils, and wires for wear or damage.
Get the full step-by-step diagnosis
Create a free Wrenchify account to unlock the rest for P0300.
Unlock diagnosisFree forever · No credit card
Related codes
See related trouble codes
Create a free Wrenchify account to unlock the rest for P0300.
Unlock related codesFree forever · No credit card
Frequently asked questions
Why is my Check Engine Light flashing with a P0300?
A flashing Check Engine Light means the misfire is severe enough to potentially damage your catalytic converter. Unburnt fuel entering the exhaust can overheat and destroy the catalyst, which is a very expensive repair.
Can a P0300 code be caused by bad gas?
Yes, contaminated or low-quality fuel can certainly lead to misfires across multiple cylinders, triggering a P0300 code. If you suspect bad gas, try filling up with premium fuel from a reputable station once the tank is low.
Get the full P0300 diagnosis for your vehicle
Year, make, model + step-by-step repair help — free plan included.