SFI SYSTEM, Diagnostic DTC:P0300, P0301, P0302, P0303, P0304

DTC Code	DTC Name
P0300	Random / Multiple Cylinder Misfire Detected
P0301	Cylinder 1 Misfire Detected
P0302	Cylinder 2 Misfire Detected
P0303	Cylinder 3 Misfire Detected
P0304	Cylinder 4 Misfire Detected

DESCRIPTION

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high hydrocarbon concentration levels can cause an increase in exhaust emission levels. Extremely high concentrations of hydrocarbons can also cause increases in the three-way catalytic converter temperature, which may cause damage to the three-way catalytic converter. To prevent this increase in emissions and to limit the possibility of thermal damage, the ECM monitors the misfire count. When the temperature of the three-way catalytic converter reaches the point of thermal degradation, the ECM blinks the MIL. To monitor misfires, the ECM uses both the camshaft position sensor and the crankshaft position sensor. The camshaft position sensor is used to identify any misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. Misfires are counted when the crankshaft rotation speed variations exceed predetermined thresholds. If the misfire count exceeds the threshold levels, and could cause emission control system performance deterioration, the ECM illuminates the MIL and stores a DTC.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory
P0300	Random / Multiple Cylinder Misfire Detected	Simultaneous misfiring of several cylinders occurs and one of the following conditions is met (2 trip detection logic): A misfire occurs that may damage the three-way catalytic converter (MIL blinks immediately when detected). An emission deterioration misfire occurs (MIL illuminates).	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Fuel injector assembly Fuel pressure Mass air flow meter Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system ECM	Comes on/Blinks* *: The MIL flashes when a catalyst-damaging misfire is detected.	DTC stored
P0301	Cylinder 1 Misfire Detected	Misfiring of the No. 1 cylinder occurs and one of the following conditions is met (2 trip detection logic): A misfire occurs that may damage the three-way catalytic converter (MIL blinks immediately when detected). An emission deterioration misfire occurs (MIL illuminates).	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Fuel injector assembly Fuel pressure Mass air flow meter Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system ECM	Comes on/Blinks* *: The MIL flashes when a catalyst-damaging misfire is detected.	DTC stored
P0302	Cylinder 2 Misfire Detected	Misfiring of the No. 2 cylinder occurs and one of the following conditions is met (2 trip detection logic): A misfire occurs that may damage the three-way catalytic converter (MIL blinks immediately when detected). An emission deterioration misfire occurs (MIL illuminates).	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Fuel injector assembly Fuel pressure Mass air flow meter Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system ECM	Comes on/Blinks* *: The MIL flashes when a catalyst-damaging misfire is detected.	DTC stored
P0303	Cylinder 3 Misfire Detected	Misfiring of the No. 3 cylinder occurs and one of the following conditions is met (2 trip detection logic): A misfire occurs that may damage the three-way catalytic converter (MIL blinks immediately when detected). An emission deterioration misfire occurs (MIL illuminates).	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Fuel injector assembly Fuel pressure Mass air flow meter Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system ECM	Comes on/Blinks* *: The MIL flashes when a catalyst-damaging misfire is detected.	DTC stored
P0304	Cylinder 4 Misfire Detected	Misfiring of the No. 4 cylinder occurs and one of the following conditions is met (2 trip detection logic): A misfire occurs that may damage the three-way catalytic converter (MIL blinks immediately when detected). An emission deterioration misfire occurs (MIL illuminates).	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Fuel injector assembly Fuel pressure Mass air flow meter Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system ECM	Comes on/Blinks* *: The MIL flashes when a catalyst-damaging misfire is detected.	DTC stored

When DTCs for misfiring cylinders are randomly stored, but DTC P0300 is not stored, it indicates that misfires have been detected in different cylinders at different times. DTC P0300 is only stored when several misfiring cylinders are detected at the same time.

MONITOR DESCRIPTION

The ECM illuminates the MIL and stores a DTC when the following condition, which could cause catalyst deterioration, is detected (2 trip detection logic).

An excessive misfiring rate (approximately 70 to 100 misfires per 1000 crankshaft revolutions) occurs a total of 4 times.

The ECM flashes the MIL (immediate detection logic) and stores a DTC (2 trip detection logic) when either one of the following conditions, which could cause damage to the three-way catalytic converter, is detected.

A sufficient amount of misfires to damage the catalyst occurring within 200 crankshaft revolutions is detected 3 times.

MONITOR STRATEGY

Required Sensors/Components (Main)

Crankshaft position sensor

Camshaft position sensor

Required Sensors/Components (Related)

Engine coolant temperature

Intake air temperature sensor

Mass air flow meter

Frequency of Operation

Continuous

TYPICAL ENABLING CONDITIONS

Misfire
Intake air temperature	Higher than -10°C (14°F)
Either of the following conditions is met	(a) or (b)
(a) Engine coolant temperature at engine start	Higher than -7°C (19°F)
(b) Engine coolant temperature	Higher than 20°C (68°F)

Monitor Period of Emission-related Misfire
Duration	Crankshaft 1000 revolutions x 4

Monitor Period of Catalyst-damaging Misfire (MIL Blinks)
Duration	Crankshaft 200 revolutions x 3

CONFIRMATION DRIVING PATTERN

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Record the DTC(s) and freeze frame data.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Switch the ECM from normal mode to check mode.

Click here
Read the misfire counts of each cylinder, Cylinder #1 Misfire Count to Cylinder #4 Misfire Count, with the engine idling. If any misfire count is displayed, skip the following confirmation driving pattern.

Drive the vehicle so that the vehicle conditions displayed in Misfire RPM and Misfire Load of the Data List are the same as the freeze frame data. Perform this step several times.

Tech Tips

In order to store misfire DTCs, it is necessary to operate the vehicle for the period of time shown in the table below, using the Misfire RPM and Misfire Load in the Data List.

Engine Speed (rpm)	Duration
Idling	8.0 minutes or more
1000	4.5 minutes or more
2000	2.5 minutes or more
3000	1.5 minutes or more

Check whether misfires have occurred by checking DTCs and freeze frame data.

Tech Tips

Do not turn the ignition switch off until the stored DTC(s) and freeze frame data have been recorded. When the ECM returns to normal mode (default), the stored DTC(s), freeze frame data and other data will be cleared.
Record the DTC(s), freeze frame data and misfire counts.
Turn the ignition switch off and wait for at least 30 seconds.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).

WIRING DIAGRAM

Refer to DTC P0102.

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Refer to Fuel Injector Circuit.

Click here

CAUTION / NOTICE / HINT

Note

Inspect the fuses for circuits related to this system before performing the following procedure.

Tech Tips

Check the "Fuel Cut Elps Time" in the Data List or the Freeze Frame Data.

If the elapsed time is over 0 seconds, then the engine speed is high (engine speed at which fuel cut occurs + 500 rpm).

When this has happened, there is the possibility that the valve rocker arm will become loose and a fire could start, so check that the valve rocker arm is properly attached.

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By clearing the DTC, "Fuel Cut Elps Time" will be cleared.
If any DTCs other than misfire DTCs are output, troubleshoot those DTCs first.
Read freeze frame data using the GTS. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.
If the misfire does not recur when the vehicle is brought to the workshop, reproduce the conditions stored in the ECM as freeze frame data.
If the misfire still cannot be reproduced even though the conditions stored in the ECM as freeze frame data have been reproduced, one of the following factors is considered to be a possible cause of the problem:

There was insufficient fuel in the tank.
Improper fuel was used.
The spark plugs have been contaminated.
The problem requires further diagnosis.

After finishing repairs, check the misfire counts of the cylinders (Cylinder #1 Misfire Count to Cylinder #4 Misfire Count).
Be sure to confirm that no misfiring cylinder DTCs are stored again by conducting the confirmation driving pattern after finishing repairs.
When one of Short FT #1 or Long FT #1 in the freeze frame data is outside the range of +/-15%, the air fuel ratio may be rich (-15% or less) or lean (+15% or more).
When Coolant Temp in the freeze frame data is less than 75°C (167°F), the misfires have occurred only while warming up the engine.
An extremely imbalanced drive wheel which causes body vibration may cause misfire DTCs to be stored.
In the past, when the primary ignition system (the igniter drive circuit in the ECM, the primary circuit in the No. 1 ignition coil, the related wire harness, or the connector) was out of order, diagnostic codes from P0351 to P0354 were output. However, these codes are not output in this vehicle.

When a failure in the primary ignition system is suspected, refer to "Cat OT MF F/C History", "Cat OT MF F/C Cylinder #1 to #4", and "Cylinder #1 Misfire Count to Cylinder #4 Misfire Count" in the freeze frame data, the pending freeze frame data, and the Data List, and confirm in which cylinder the high-frequency misfire was concentrated.
Referring to the following contents of the freeze frame data (or the pending freeze frame data) enables an estimation of which cylinder has misfired and to what degree.

Cylinder #1 Misfire Count to Cylinder #4 Misfire Count: Misfire count according to cylinder.
Cat OT MF F/C Cylinder #1 to #4: This expresses a high-frequency misfire was concentrated in a certain cylinder and that cylinder's fuel injection was stopped.

PROCEDURE

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO MISFIRE DTCS)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

Powertrain > Engine and ECT > Trouble Codes

Read the DTCs.

Result

Result	Proceed to
DTC P0300, P0301, P0302, P0303 and/or P0304 are output	A
DTC P0300, P0301, P0302, P0303 and/or P0304 and other DTCs are output	B

Tech Tips

If any DTCs other than P0300, P0301, P0302, P0303 and P0304 are output, troubleshoot those DTCs first.

GO TO DTC CHART Click here

CHECK PCV HOSE CONNECTIONS

Check the PCV hose connections.