P0300 Diagnostic Code - Random Misfire
Symptoms.
Engine may stumble or miss
Engine may be hard to start
you may notice no issues
Cause
Failing spark plugs or spark plug wires
Bad coil or coil pack
Failing oxygen sensor(s)
Bad fuel injector or more than one
Stuck exhaust valve
Bad catalytic converter
EGR valve or valve passage clogging
Bad camshaft position sensor
Bad PCM or ECM
The Fix
Best first action is a tune up, new plugs, wires, inspect all hoses and wire connections then reset the code. If it returns you will need to narrow it down to a system, coils and coil packs should be tested, catalytic converters for function ( do you smell rotten eggs?). A misfire that jumps cylinders could indicate a lean condition, do you have any other codes along with the 300? this will help clue you in to the source, check valve function to make sure they are opening and closing fully.
This is probably pone of the most difficult codes to troubleshoot, so start with the basics and work your way into the more expensive options, in many cases a good old tune up solves the problem, back it up with a fuel system cleaning and see where you stand.
Random/multiple misfire
Random/multiple misfire
P0300 is multiple or random cylinder misfire. No start can be dead battery, failed starter, no fuel, no fuel pressure, computer or sensor malfunction, internal engine failure, etc.
P0300 is multiple or random cylinder misfire.
OBD-1. 1995 was a changeover year. All 1995 cars/trucks (GM to my knowledge, I don't know about the other brands) were OBD-1 and some have an OBD-2 connector, but still are OBD-1.
One that works with OBD II.
Evap Leak
Trouble code P1111 means: IAT Sensor Circuit Intermittent Voltage High
OBD II. OBD I phased out in the mid 90's.
Trouble code P0501 means:Vehicle speed sensor range/performace
Trouble code P0440 means: EVAP System No Flow During Purge
What does obd code P0740 mean
It is immediately under dash near steering column.
Trouble code P0442 means: Evaporative Emission System Leak Detected (small leak)