April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P0300-00; Random Misfire Detected: Notes

NOTE:

To determine the malfunctioning part, proceed with the diagnostics from "Function Inspection Using M-MDS".

Details On DTCs

DETECTION CONDITION AND POSSIBLE CAUSE

DESCRIPTION	Random misfire detected
DETECTION CONDITION	Determination conditions	Any one of the following conditions is met: The misfire rate for every 200 rotations of the crankshaft exceeds the specified value (misfire which may damage catalytic converter). The misfire rate for every 1, 000 rotations of the crankshaft exceeds the specified value (misfire going against emission regulations).
	Preconditions	Battery voltage: 9-18 V^1 Engine speed: 500-6, 000 rpm^1 Engine coolant temperature: 20 °C {68 °F} or more^1 Not cranking Not stalling Fuel-cut control not implemented Crankshaft installation tolerance learning completed Engine condition is stabilized (not directly after gear change) ^1 : Value can be verified by displaying PIDs using the M-MDS
	Malfunction determination period	200 rotations of crankshaft (misfire which may damage catalytic converter) 1, 000 rotations of crankshaft (misfire going against emission regulations)
	Drive cycle	2
	Self test type	CMDTC self test
	Sensor used	CKP sensor MAF sensor MAP sensor
FAIL-SAFE FUNCTION	Limits intake air amount Implement fuel-cut control (if the catalytic converter may be damaged, perform fuel-cut on cylinder misfiring the most).
VEHICLE STATUS WHEN DTCs ARE OUTPUT	Misfiring which may damage catalytic converter (number of drive cycles: 1): Check engine light flashes and pending code is recorded Drive cycle directly after above drive cycle (number of drive cycles: 2): Malfunction determined: check engine light is illuminated Normal is determined: Pending code cleared Rough idling, poor acceleration, stalling
POSSIBLE CAUSE	Improper operation of ignition system Spark plug malfunction Ignition coil related wiring harness or connector malfunction Ignition coil malfunction Fuel injector malfunction Improper operation of fuel injector Fuel injector related wiring harness malfunction Erratic signal to PCM CKP sensor signal malfunction ECT sensor No. 1 signal malfunction MAF sensor signal malfunction MAP sensor signal malfunction IAT sensor No. 1 signal malfunction APP sensor signal malfunction TP sensor signal malfunction VSS signal malfunction Related connector or terminals malfunction Related wiring harness malfunction Poor drive belt assembly or adhesion of oil Drive belt auto tensioner malfunction Air leakage from intake air system (between intake manifold and cylinder head) Engine malfunction Insufficient engine compression Engine coolant leakage to combustion chamber PCM malfunction