Spark Plugs
Spark Plug Wires
Ignition Coils
EGR Valve
Mass Air Flow (MAF) Sensor
Crankshaft Position Sensor
The necessary parts and tools to clear this Diagnostic Trouble Code (DTC) might differ depending on your vehicle's make and model. If your Check Engine light is illuminated, stop by any O’Reilly Auto Parts and get an O’Reilly VeriScan® for your car, truck, or SUV and get a detailed VeriScan report with more information about your vehicle’s Diagnostic Trouble Code(s), along with possible causes and repair solutions. If you aren’t comfortable making these repairs yourself, our parts professionals can recommend a local shop to make your repair.
OBD-II fault code P0300 means “Random or Multiple Cylinder Misfire Detected”, and typically appears when a cylinder fails to produce power or combustion doesn’t occur because of a lack of spark, fuel, or compression. Since this code indicates one or more misfiring cylinders, you’ll typically see it in conjunction with a code or codes indicating specifically which of your cylinders are misfiring.
P0300 Code Diagnosis
When you experience a P0300 diagnostic trouble code, your vehicle may be experiencing failure in one of a few areas:
- Spark plugs
- Ignition wires
- Ignition coils
- Distributor cap and rotor
- Ignition timing
- Vacuum integrity
- Fuel pressure
- Exhaust gas recirculation system
- Mass airflow (MAF) sensor
- Crankshaft position sensor
- Valves
- Head gasket
P0300 OBD-II Code Symptoms
Symptoms of a P0300 Code can include:
- Check Engine light
- Rough running/idling
- Lack of power
- Hesitation/jerking
- Dying at stops
- Poor fuel economy
If you’re comfortable diagnosing the issue yourself, or if you have other codes related to these symptoms, you may be able to determine the cause of your P0300 code with a physical inspection. One of the easiest tests you can perform is to determine whether this may be related to a fouled spark plug or damaged ignition coil. If your vehicle is equipped with coil packs, you can swap a coil from a cylinder that is not experiencing the misfire to the one that is misfiring. If the code moves to a different cylinder, then you know you have a bad coil. If it doesn’t, you can also swap or check your spark plugs to ensure they are in good condition and not excessively worn. A compression test can also help you determine if the misfiring cylinder has adequate compression for combustion, and a compression tester is available in our Loaner Tool program.
Whether you notice any symptoms or not, it is not recommended that you drive a vehicle with this code until the problem is diagnosed.
Risks of Driving with a P0300 Code:
Your vehicle may still run, but driving has the potential to make the problem worse or cause damage to other systems.
