Troubleshooting by Diagnostic Trouble Code - DTC P0300

DESCRIPTION AND OPERATION

When the ignition switch is in the "ON" or "START" position, voltage is supplied to the ignition coil. The ignition coil consists of two windings (primary and secondary). High-voltage spark plug wires connect the ignition coils to the spark plug of each engine cylinder. The ignition coil produces a spark (discharge) from the spark plugs on each power stroke (for the cylinder on the compression stroke and for the cylinder on the exhaust stroke). The first ignition coil fires the spark plugs of cylinders No. 1 and No. 4. The second ignition coil fires the spark plugs of cylinders No. 2 and No. 3.

The engine control module contains a ground-switching circuit that energizes the ignition coil primary winding. The engine control module uses the crankshaft position sensor signal to determine when to energize the winding. After the current in the ignition coil primary circuit is interrupted (switched on and off), a high-voltage pulse is induced in the secondary winding, which produces a spark at the connected spark plugs.

DTC SET CONDITIONS

The engine control module will store DTC P0300 and illuminate the malfunction indicator lamp if, during two driving cycles, 2 misfires per 100 crankshaft revolutions are detected. Misfire frequency is measured every 200 crankshaft revolutions when the following conditions are met:

• Change in crankshaft speed per second is less than 1000 rpm.

• Crankshaft speed is within 600 - 4000 rpm.

• Engine load (injector pulse width) is greater than 2 msec.

• No fuel cut-off is active.

• Starter is not operating.

• Vehicle is driving on a level road (acceleration value less than 0.3 g according to the acceleration sensor).

If the misfire rate increases to 5 - 25% per 200 crankshaft revolutions, there is a risk of catalytic converter damage and the malfunction indicator lamp will flash. The catalytic converter temperature may exceed 1950°C (3542°F) if the misfire rate increases further. This code indicates an ignition system malfunction detected by the engine control module.

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECTION PROCEDURE