DTC P0300 - P0304 NO. 4 - 1 CYLINDER MISFIRE, MULTIPLE CYLINDER MISFIRE - On Board Diagnosis Logic / DTC Confirmation Procedure

If a misfire occurs, the engine speed will fluctuate. If the fluctuation is detected by the crankshaft position sensor (POS), the misfire is diagnosed.

The misfire detection logic consists of the following two conditions.

1. One Trip Detection Logic (Three Way Catalyst Damage) When a misfire is detected which will overheat and damage the three way catalyst, the MI will start blinking; even during the first trip. In this condition, ECM monitors the misfire every 200 revolutions. If the misfire frequency decreases to a level that will not damage the three way catalyst, the MI will change from blinking to lighting up. (After the first trip detection, the MI will light up from engine starting. If a misfire is detected that will cause three way catalyst damage, the MI will start blinking.)

2. Two Trip Detection Logic (Exhaust quality deterioration) When a misfire that will not damage the three way catalyst (but will affect exhaust emission) occurs, the MI will light up based on two trip detection logic. In this condition, ECM monitors the misfire for every 1,000 revolutions of the engine.