DTC P0300: Random/Multiple Cylinder Misfire Detected

Random Misfire Circuit
• Refer to, DTC P0201 - P0204 Injector Circuit Malfunction .
CIRCUIT OPERATION
• Refer to, DTC P0201 - P0204 Injector Circuit Malfunction .
TECHNICAL DESCRIPTION
• If a misfire occurs while the engine is running, the engine speed changes for an instant.
• The ECM <M/T> or PCM <A/T> checks for such changes in engine speed.
DTC SET CONDITIONS

Check Conditions
Engine speed is between 500 and 6,000 r/min.
Engine coolant temperature is higher than -10°C (14°F).
Intake air temperature is higher than -10°C (14°F).
Barometric pressure is higher than 76 kPa (11 psi).
Adaptive learning is complete for the vane which generates a crankshaft position signal.
While the engine is running, excluding gear shifting, deceleration, sudden acceleration/deceleration and A/C compressor switching.
The throttle deviation is -0.059 volt/10 ms to +0.059 volt/10 ms.

Judgement Criteria (change in the angular acceleration of the crankshaft is used for misfire detection).
• Misfire has occurred more frequently than allowed during the last 200 revolutions [when the catalyst temperature is higher than 950°C (1742°F)].
or
• Misfire has occurred in 19 or more of the last 1,000 revolutions (corresponding to 1.5 times the limit of emission standard).
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 14 .
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:
• Ignition system related part(s) failed.
• Poor crankshaft position sensor.
• Incorrect air/fuel ratio.
• Low compression pressure.
• Skipping of timing belt teeth.
• EGR system and EGR valve failed.
• ECM failed. <M/T>
• PCM failed. <A/T>