Some are:
• Worn spark plugs
• Cracked distributor caps
• Out of Phase distributor/rotor
• Shorted rotors
• Leaking plug wires
• Low fuel pressure
• Low compression
• Sticking valves
• Broken valve springs
• Worn cam lobes
• Incorrect valve or ignition timing
• Leaking EGR
• Vacuum leaks
• Leaking Injectors
• Clogged Injectors
• Contaminated fuel
• Low fuel tank level
• Excessive EVAP purge
• Low ignition system primary voltage
• Cracked coils
• Plugged exhaust
• Excessive PCV flow
• Wiring Harness
• Faulty PCM
Trouble code P0300 means: Random/multiple cylinder misfire detected
Random misfire, cylinder 2 misfire, and cylinder 3 misfire. see related question below.
Its a random misfire detected
answer : Random Misfire
You locate the cause of the random misfire and take corrective actions against that; be it a coil, plug, wire, coil boot or crank sensor. A random misfire is as it states - a misfire that happens randomly in possibly a random cylinder as well. They can be hard to diagnose, as well and it is recommended that you take vehicle to a qualified, ASE certified shop for diagnostics.
po300-Random/multiple cylinder misfire detected. po303-Cylinder no. 3 misfire detected. po306-cylinder no. 6 misfire detected po300-Random/multiple cylinder misfire detected. po303-Cylinder no. 3 misfire detected. po306-cylinder no. 6 misfire detected
P0303 is cylinder #3 misfire. P0300 would be random misfire. Either way you need to diagnose the case of a misfire. Check spark plugs, plug wires(if equipped), cylinder compression, fuel inectors, and wiring.
It means that more than one cylinder has a misfire history. PO301 would be cylinder number 1 misfire. PO302 would be number 3 cylinder misfire.
Multiple & or random misfire(s)
Tune up
Random/multiple misfire detected.
P0300 is multiple or random cylinder misfire.