DTC P0300: Notes

DTC P0300 DETECTION & CONDITION POSSIBLE CAUSES

DTC P0300	Random misfire detected
DETECTION CONDITION	The PCM monitors the eccentric shaft position sensor input signal interval time. The PCM calculates the change of the interval time for each rotor. If the change of interval time exceeds the preprogrammed criteria, the PCM detects a misfire in the corresponding rotor. While the engine is running, the PCM counts the number of misfires that occurred at 200 eccentric shaft revolutions and 1,000 eccentric shaft revolutions and calculates the misfire ratio for each eccentric shaft revolution. If the ratio exceeds the preprogrammed criteria, the PCM determines that a misfire, which can damage the catalytic converter or affect emission performance, has occurred. Diagnostic support note This is a continuous monitor (Misfire). The MIL illuminates if the PCM detects the misfire which affects emission performance in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM. The MIL flashes if the PCM detects the misfire which can damage the catalytic converter during the first drive cycle. Therefore, PENDING CODE is not available while the MIL flashes. PENDING CODE is available if the PCM detects the misfire which affects emission performance during the first drive cycle. FREEZE FRAME DATA is available. The DTC is stored in the PCM memory.
POSSIBLE CAUSE	Eccentric shaft position sensor malfunction Ignition system malfunction High-tension lead malfunction Incorrect power supply to ignition coil Ignition coil malfunction Spark plug malfunction MAF sensor malfunction Excess air suction in intake-air system Fuel line pressure malfunction Fuel pump unit malfunction Leakage fuel Insufficient compression Metering oil pump malfunction Engine oil condition malfunction Increased oil pressure Oil passage malfunction Engine malfunction ECT sensor malfunction Purge control system malfunction Leakage engine coolant PCM malfunction

DTC P0300

Random misfire detected

DETECTION CONDITION

The PCM monitors the eccentric shaft position sensor input signal interval time. The PCM calculates the change of the interval time for each rotor. If the change of interval time exceeds the preprogrammed criteria, the PCM detects a misfire in the corresponding rotor. While the engine is running, the PCM counts the number of misfires that occurred at 200 eccentric shaft revolutions and 1,000 eccentric shaft revolutions and calculates the misfire ratio for each eccentric shaft revolution. If the ratio exceeds the preprogrammed criteria, the PCM determines that a misfire, which can damage the catalytic converter or affect emission performance, has occurred.

Diagnostic support note

This is a continuous monitor (Misfire).
The MIL illuminates if the PCM detects the misfire which affects emission performance in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
The MIL flashes if the PCM detects the misfire which can damage the catalytic converter during the first drive cycle. Therefore, PENDING CODE is not available while the MIL flashes.
PENDING CODE is available if the PCM detects the misfire which affects emission performance during the first drive cycle.
FREEZE FRAME DATA is available.
The DTC is stored in the PCM memory.

POSSIBLE CAUSE

Eccentric shaft position sensor malfunction
Ignition system malfunction
- High-tension lead malfunction
- Incorrect power supply to ignition coil
- Ignition coil malfunction
- Spark plug malfunction
MAF sensor malfunction
Excess air suction in intake-air system
Fuel line pressure malfunction
Fuel pump unit malfunction
Leakage fuel
Insufficient compression
- Metering oil pump malfunction
- Engine oil condition malfunction
- Increased oil pressure
- Oil passage malfunction
- Engine malfunction
ECT sensor malfunction
Purge control system malfunction
Leakage engine coolant
PCM malfunction