SFI SYSTEM, Diagnostic DTC:P0300, P0301, P0302, P0303, P0304, P0305, P0306

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
P0305	Cylinder 5 Misfire Detected
P0306	Cylinder 6 Misfire Detected

DESCRIPTION

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high hydrocarbons concentration levels can cause increases in exhaust emission levels. 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 these increases 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 VVT sensor and the crankshaft position sensor. The VVT 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 level and could cause emission deterioration, the ECM illuminates the MIL and sets a DTC.

DTC No.	DTC Detection Condition	Trouble Area
P0300	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 when detect immediately). 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 Fuel system Mass air flow meter Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system ECM
P0301 P0302 P0303 P0304 P0305 P0306	Misfiring of a specific 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 when detect immediately). An emission deterioration misfire occurs (MIL illuminates).

DTC No.

DTC Detection Condition

Trouble Area

P0300

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 when detect immediately).
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
Fuel system
Mass air flow meter
Engine coolant temperature sensor
Compression pressure
Valve timing
PCV valve and hose
PCV hose connections
Intake system
ECM

P0301

P0302

P0303

P0304

P0305

P0306

Misfiring of a specific 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 when detect immediately).
An emission deterioration misfire occurs (MIL illuminates).

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 sets a DTC when either one of the following conditions, which could cause emission deterioration, is detected (2 trip detection logic).

An excessive misfiring rate (approximately 20 to 50 misfires per 1000 crankshaft revolutions) occurs a total of 4 times.

The ECM flashes the MIL (immediate detection logic) and sets a DTC (2 trip detection logic) when either one of the following conditions, which could cause the Three-Way Catalytic Converter (TWC) damage, 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, VVT sensor
Required Sensors/Components (Related)	Engine coolant temperature and intake air temperature sensors and mass air flow meter
Frequency of Operation	Continuous

TYPICAL ENABLING CONDITIONS

Misfire
Either of the following conditions is met:	Condition (a) or (b)
(a) Engine coolant temperature at engine start	More than -7°C (19°F)
(b) Engine coolant temperature	More than 20°C (68°F)

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

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

CONFIRMATION DRIVING PATTERN

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
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) Click here.
Using the GTS, switch the ECM from normal mode to check mode Click here.
Read the misfire counts of each cylinder (Cylinder #1 (to #6) Misfire Count) with the engine idling. If any misfire count is displayed, skip the following confirmation driving pattern.

Drive the vehicle several times with the conditions, such as engine speed and engine load, shown in Misfire RPM and Misfire Load in the freeze frame data.

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. Confirm Misfire RPM and Misfire Load in the Data List.

Engine Speed	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 engine 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 engine switch off and wait for at least 30 seconds.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) Click here.

INSPECTION PROCEDURE

Tech Tips

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 volume in the tank.
Improper fuel is used.
The spark plugs have been contaminated.

After finishing repairs, check the misfire counts of the cylinders (Cylinder #1 Misfire Count to Cylinder #6 Misfire Count).
Be sure to confirm that no misfiring cylinder DTCs are set again by conducting the confirmation driving pattern after finishing repairs.
For 6 cylinder engine, the ECM intentionally does not set the specific misfiring cylinder DTCs at high engine speed. If misfires occur only in high engine speed areas, only DTC P0300 is set.

In the event of DTC P0300 being present, perform the following operations:

Clear the DTCs Click here.
Start the engine and conduct the confirmation driving pattern.
Read the misfiring rates of each cylinder or DTC(s) using the GTS.
Repair the cylinder(s) that has a high misfiring rate or is indicated by the DTC.
After finishing repairs, conduct the confirmation driving pattern again, in order to verify that DTC P0300 is not set.

When one of Short FT #1, Long FT #1, Short FT #2 or Long FT #2 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 the Coolant Temp in the freeze frame data is less than 75°C (167°F), the misfires have occurred only while the engine is being warmed up.
An extremely imbalanced drive wheel which causes body vibration may cause misfire DTCs detection.

PROCEDURE

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

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

Read the DTCs.

Result

Result	Proceed to
P0300, P0301, P0302, P0303, P0304, P0305 and/or P0306	A
P0300, P0301, P0302, P0303, P0304, P0305 and/or P0306 and other DTCs	B

Tech Tips

If any DTCs other than P0300, P0301, P0302, P0303, P0304, P0305 and P0306 are output, troubleshoot those DTCs first.

GO TO DTC CHART Click here

CHECK PCV HOSE CONNECTIONS
1. Check the PCV hose (w/ canister pump module) connections Click here
2. Check the PCV hose (w/o canister pump module) connections Click here
  
  OK
  
  PCV valve and hose are connected correctly and are not damaged.
NG
REPAIR OR REPLACE PCV HOSE

OK
READ VALUE USING GTS (MISFIRE RPM AND MISFIRE LOAD)
1. Connect the GTS to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the GTS on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / Gas Misfire / Misfire RPM and Misfire Load.
5. Read and note the Misfire RPM and Misfire Load values.
  
  Tech Tips
  
  The Misfire RPM and Misfire Load values indicate the vehicle conditions under which the misfire occurred.
NEXT

OK
PCV valve and hose are connected correctly and are not damaged.

READ VALUE USING GTS (CATALYST OT MF F/C)

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Data List / Gas Misfire / Catalyst OT MF F/C.

Read the value displayed on the GTS.

Result

Data List	GTS Display	Proceed to
Catalyst OT MF F/C	Avail	A
Catalyst OT MF F/C	Not Avl	B

READ VALUE USING GTS (CYLINDER #1 (to #6) MISFIRE COUNT) Click here

PERFORM ACTIVE TEST USING GTS
1. Connect the GTS to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the GTS on.
4. Enter the following menus: Powertrain / Engine and ECT / Active Test / Prohibit the Catalyst OT Misfire prevent F/C.
5. Perform the Active Test.
  
  Note
  
  When performing the Active Test, make sure the vehicle is stopped and the engine is either idling or being revved at 3000 rpm or less.
NEXT

READ VALUE USING GTS (CYLINDER #1 (to #6) MISFIRE COUNT)

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Data List / Gas Misfire / Cylinder #1 Misfire Count, Cylinder #2 Misfire Count, Cylinder #3 Misfire Count, Cylinder #4 Misfire Count, Cylinder #5 Misfire Count and Cylinder #6 Misfire Count.
Start the engine and allow the engine to idle.
Read each value for Cylinder #1 Misfire Count to Cylinder #6 Misfire Count displayed on the GTS. If no misfire counts occur in any cylinders, perform procedure [A] and [B] and then check the misfire counts again.
Drive the vehicle with the Misfire RPM and Misfire Load noted in the "Read Value Using GTS (Misfire RPM And Misfire Load)" procedures above [A].

Read the Cylinder #1 Misfire Count to Cylinder #6 Misfire Count or DTCs displayed on the GTS [B].

Result
Result	Proceed to
Most misfires occur in only 1 or 2 cylinders	A
3 cylinders or more have equal misfire counts	B

Tech Tips

If it is difficult to reproduce misfires for each cylinder, check the Data List item called Misfire Margin. Try to find vehicle driving conditions that lower the Misfire Margin value. Values above 30% are considered normal.
If the freeze frame data record of the engine coolant temperature is less than 75°C (167°F), the misfire may be detected only when the engine is cold.
If the freeze frame data record of the Engine Run Time is below 120 seconds, the misfire may be detected immediately after the engine is started.

CHECK INTAKE SYSTEM Click here

INSPECT SPARK PLUG
1. Inspect the spark plug of the misfiring cylinder Click here.
NG
REPLACE SPARK PLUG Click here

OK
CHECK FOR SPARK (SPARK TEST)
1. Perform a spark test Click here.
  
  Tech Tips
  
  If the result of the spark test is normal, proceed to the next step.
NEXT
CHECK CYLINDER COMPRESSION PRESSURE
1. Measure the cylinder compression pressure of the misfiring cylinder Click here.
NG
CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

OK
CHECK FUEL INJECTOR ASSEMBLY OF MISFIRING CYLINDER
1. Check the resistance of the fuel injector assembly Click here.
2. Inspect the cold start injector Click here.
NG
REPLACE FUEL INJECTOR ASSEMBLY Click here

OK
CHECK INTAKE SYSTEM
1. Check the intake system for vacuum leaks Click here.
  
  OK
  
  No leaks from intake system.
NG
REPAIR OR REPLACE INTAKE SYSTEM

OK
CHECK FUEL PRESSURE
1. Check the fuel pressure for low pressure side Click here.
2. Check the fuel pressure for high pressure side Click here.
NG
REPAIR OR REPLACE FUEL SYSTEM

OK

OK
No leaks from intake system.

READ VALUE USING GTS (COOLANT TEMP)

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.

Read the Coolant Temp twice, when the engine is both cold and warmed up.

Standard
With cold engine
Same as ambient temperature.
With warm engine
Between 75 and 100°C (167 and 212°F).

REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here

READ VALUE USING GTS (MAF)
1. Connect the GTS to the DLC3.
2. Start the engine.
3. Turn the GTS on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF and Coolant Temp.
5. Allow the engine to idle until Coolant Temp reaches 75°C (167°F) or higher.
6. Read MAF with the engine speed at 3000 rpm.
  
  Standard
  
  Between 7.60 gm/sec. and 11.40 gm/sec. (shift lever: Neutral position, A/C: Off).
NG
CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER CONNECTOR CONNECTION) Click here

OK

Standard
Between 7.60 gm/sec. and 11.40 gm/sec. (shift lever: Neutral position, A/C: Off).

CHECK VALVE TIMING

Text in Illustration

*1 Timing Mark

Remove the cylinder head cover sub-assemblies RH and LH.
Turn the crankshaft to align the timing marks of the crankshaft.
Align the notch of the crankshaft pulley to the "0" position.
Check if the timing marks of the camshaft pulley and camshaft bearing cap align.

Text in Illustration
*1	Timing Mark

Turn the crankshaft clockwise 360° if the timing marks do not align. Check if they align once again.

OK
The timing marks of the camshaft pulley and the camshaft bearing cap align when the notch of the crankshaft pulley is in the "0" position.

Reinstall the cylinder head cover sub-assemblies RH and LH.

CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER CONNECTOR CONNECTION) Click here

CHECK ENGINE MECHANICAL SYSTEM Click here

CHECK INTAKE SYSTEM
1. Check the intake system for vacuum leaks Click here.
  
  OK
  
  No leaks from intake system.
NG
REPAIR OR REPLACE INTAKE SYSTEM

OK
CHECK FUEL PRESSURE
1. Check the fuel pressure for low pressure side Click here.
2. Check the fuel pressure for high pressure side Click here.
NG
REPAIR OR REPLACE FUEL SYSTEM

OK

OK
No leaks from intake system.

READ VALUE USING GTS (COOLANT TEMP)

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.

Read the Coolant Temp twice, when the engine is both cold and warmed up.

Standard
With cold engine
Same as ambient temperature.
With warm engine
Between 75 and 100°C (167 and 212°F).

REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here

READ VALUE USING GTS (MAF)
1. Connect the GTS to the DLC3.
2. Start the engine.
3. Turn the GTS on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF and Coolant Temp.
5. Allow the engine to idle until Coolant Temp reaches 75°C (167°F) or higher.
6. Read MAF with the engine speed at 3000 rpm.
  
  Standard
  
  Between 7.60 g/sec. and 11.40 g/sec. (shift lever: Neutral position, A/C: Off).
NG
CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER CONNECTOR CONNECTION) Click here

OK

CHECK VALVE TIMING

Text in Illustration

*1 Timing Mark

Remove the cylinder head cover sub-assemblies RH and LH.
Turn the crankshaft to align the timing marks of the crankshaft.
Align the notch of the crankshaft pulley to the "0" position.
Check if the timing marks of the camshaft pulley and camshaft bearing cap align.

Turn the crankshaft clockwise 360° if the timing marks do not align. Check if they align once again.

OK
The timing marks of the camshaft pulley and the camshaft bearing cap align when the notch of the crankshaft pulley is in the "0" position.

Reinstall the cylinder head cover sub-assemblies RH and LH.

CHECK ENGINE MECHANICAL SYSTEM Click here

INSPECT SPARK PLUG
1. Inspect the spark plug of the misfiring cylinder Click here.
NG
REPLACE SPARK PLUG Click here

OK
CHECK FOR SPARK (SPARK TEST)
1. Perform a spark test Click here.
  
  Tech Tips
  
  If the result of the spark test is normal, proceed to the next step.
NEXT
CHECK CYLINDER COMPRESSION PRESSURE
1. Measure the cylinder compression pressure of the misfiring cylinder Click here.
NG
CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

OK
CHECK FUEL INJECTOR ASSEMBLY OF MISFIRING CYLINDER
1. Check the resistance of the fuel injector assembly Click here.
2. Inspect the cold start injector Click here.
NG
REPLACE FUEL INJECTOR ASSEMBLY Click here

OK
CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER CONNECTOR CONNECTION)
1. Check the connection and terminal contact pressure of connectors and wire harnesses between the mass air flow meter and ECM Click here.
  
  Tech Tips
  
  Repair any problems.
NEXT

CHECK WHETHER DTC OUTPUT RECURS

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Clear the DTCs Click here.
Turn the engine switch off and wait for at least 30 seconds.
Turn the engine switch on (IG) and turn the GTS on.
Start the engine and warm it up.
Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0300, P0301, P0302, P0303, P0304, P0305 or P0306.

Check the DTC judgment result.

Result

Proceed to

ABNORMAL

(DTC P0300, P0301, P0302, P0303, P0304, P0305 and/or P0306 is output)

NORMAL

(DTC is not output)

END

CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)

Disconnect the mass air flow meter connector.
Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance

Tester Connection	Condition	Specified Condition
F39-5 (VG) - F1-25 (VG)	Always	Below 1 Ω
F39-4 (E2G) - F1-24 (E2G)	Always	Below 1 Ω
F39-5 (VG) or F1-25 (VG) - Body ground	Always	10 kΩ or higher

Reconnect the mass air flow meter connector.
Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER - ECM)

REPLACE MASS AIR FLOW METER
1. Replace the mass air flow meter Click here.
  
  Tech Tips
  
  If the results of the inspections performed in steps 14 and 19 indicated no problem, proceed to the next step without replacing the mass air flow meter.
NEXT

CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Clear the DTCs Click here.
Turn the engine switch off and wait for at least 30 seconds.
Turn the engine switch on (IG) and turn the GTS on.
Start the engine and warm it up.
Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0300, P0301, P0302, P0303, P0304, P0305 or P0306.

Check the DTC judgment result.

Result

Proceed to

NORMAL

(DTC is not output)

ABNORMAL

(DTC P0300, P0301, P0302, P0303, P0304, P0305 and/or P0306 is output)

REPLACE ECM Click here

END