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 cam position sensor and the crank position sensor. The cam position sensor is used to identify any misfiring cylinders and the crank 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 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 connections Vacuum hose connections Ignition system Fuel injector assembly Fuel pressure Fuel line Fuel pump Mass air flow meter sub-assembly Engine coolant temperature sensor Compression pressure Valve timing PCV valve and hose PCV hose connections Intake system EGR valve assembly ECM
P0301 P0302 P0303 P0304	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 connections
Vacuum hose connections
Ignition system
Fuel injector assembly
Fuel pressure
Fuel line
Fuel pump
Mass air flow meter sub-assembly
Engine coolant temperature sensor
Compression pressure
Valve timing
PCV valve and hose
PCV hose connections
Intake system
EGR valve assembly
ECM

P0301

P0302

P0303

P0304

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 stores a DTC when the following condition, which could cause catalyst 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 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)

Crank position sensor

Cam position sensor

Required Sensors/Components (Related)

Engine coolant temperature

Intake air temperature sensor

Mass air flow meter sub-assembly

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 Click here.

Refer to Fuel Injector Circuit Click here.

CAUTION / NOTICE / HINT

Note

Inspect the fuses for circuits related to this system before performing the following 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 in the tank.
Improper fuel is 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 set again by conducting the confirmation driving pattern after finishing repairs.
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 warming up the engine.
An extremely imbalanced drive wheel which causes body vibration may cause misfire DTCs to be stored.

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.

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 (HOSE CONNECTIONS)
1. Check the PCV hose connections Click here.
  
  OK
  
  PCV valve and hose are correctly connected 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 ignition switch to ON.
3. Turn the GTS on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / 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 correctly connected and are not damaged.

READ VALUE USING GTS (CYLINDER #1 MISFIRE COUNT, #2, #3 AND #4)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Cylinder #1 Misfire Count, Cylinder #2 Misfire Count, Cylinder #3 Misfire Count and Cylinder #4 Misfire Count.
Start the engine and allow the engine to idle.
Read each value for Cylinder #1 Misfire Count to Cylinder #4 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 #4 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 below 75°C (167°F), it may only be possible to detect the misfire 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.
  
  Tech Tips
  
  Perform "Inspection After Repair" after replacing the spark plug Click here.
NG
REPLACE SPARK PLUG Click here

OK
CHECK FOR SPARKS (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.
  - Perform "Inspection After Repair" after repairing or replacing the ignition system Click here.
NEXT
CHECK CYLINDER COMPRESSION PRESSURE
1. Measure the cylinder compression pressure of the misfiring cylinder Click here.
  
  Tech Tips
  
  Perform "Inspection After Repair" after repairing or replacing the engine assembly Click here.
NG
CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

OK

CHECK TERMINAL VOLTAGE (POWER SOURCE OF FUEL INJECTOR ASSEMBLY)

Text in Illustration

*a
Front view of wire harness connector

(to ECM)

Disconnect the ECM connector.
Turn the ignition switch to ON.

Text in Illustration
*a	Front view of wire harness connector (to ECM)

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

Standard Voltage

Tester Connection	Condition	Specified Condition
B23-20 (#10) - B23-51 (E01)	Ignition switch ON	11 to 14 V
B23-17 (#20) - B23-51 (E01)	Ignition switch ON	11 to 14 V
B23-18 (#30) - B23-51 (E01)	Ignition switch ON	11 to 14 V
B23-19 (#40) - B23-51 (E01)	Ignition switch ON	11 to 14 V

CHECK FUEL INJECTOR CIRCUIT Click here

CHECK FUEL INJECTOR ASSEMBLY OF MISFIRING CYLINDER
1. Check the fuel injector assembly injection (whether fuel volume is high or low, and whether injection pattern is poor) Click here.
  
  Tech Tips
  
  Perform "Inspection After Repairs" after replacing the fuel injector assembly 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 in intake system.
  
  Tech Tips
  
  Perform "Inspection After Repair" after repairing or replacing the intake system Click here.
NG
REPAIR OR REPLACE INTAKE SYSTEM

OK
CHECK FUEL PRESSURE
1. Check the fuel pressure Click here.
NG
CHECK FUEL LINE Click here

OK

OK
No leaks in intake system.

READ VALUE USING GTS (COOLANT TEMP)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Coolant Temp.

Read the Data List twice, when the engine is both cold and warmed up.

Standard

GTS Display	Condition	Specified Condition
Coolant Temp	Cold engine	Same as ambient air temperature
Coolant Temp	Warm engine	Between 75 and 100°C (167 and 212°F)

Tech Tips

Perform "Inspection After Repair" after replacing the engine coolant temperature sensor ( Click here).

REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here

READ VALUE USING GTS (MAF)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF, Coolant Temp and Engine Speed.

Read MAF with the engine speed 3000 rpm.

Standard

GTS Display

Condition

Specified Condition

MAF

Shift lever position: N

A/C: off

Engine Speed: 3000 rpm

Between 4 gm/sec. and 10 gm/sec

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

PERFORM ACTIVE TEST USING GTS (CONTROL THE EGR STEP POSITION)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or more.

Tech Tips

The A/C switch and all accessory switches should be off.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position / All Data / MAP.

Check the engine idling condition and MAP values in the Data List while performing the Active Test.

Tech Tips

Do not leave the EGR valve open for 10 seconds or more during the Active Test.
Be sure to return the EGR valve to step 0 when the Active Test is completed.
Do not open the EGR valve 30 steps or more during the Active Test.

OK
MAP and idling condition change in response to EGR step position.

Standard

EGR Step Position (Active Test)

0 Steps

0 to 30 Steps

Idling condition

Steady idling

Idling changes from steady to rough idling or engine stalls

MAP

(Data List)

MAP value is 20 to 48 kPa(abs) [150 to 360 mmHg(abs)]

(EGR valve is fully closed)

MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed

Result
Result	Proceed to
NG	A
OK	B

Tech Tips

During Active Test, if the idling condition does not change in response to EGR step position, then there is probably a malfunction in the EGR valve.

ADJUST VALVE TIMING Click here

INSPECT EGR VALVE ASSEMBLY
1. Remove the EGR valve assembly Click here.
2. Check if the EGR valve is stuck open.
  
  OK
  
  EGR valve is tightly closed.
  
  Tech Tips
  
  Perform "Inspection After Repair" after replacing the EGR valve assembly Click here.
NG
REPLACE EGR VALVE ASSEMBLY Click here

OK
ADJUST VALVE TIMING

Tech Tips

There are no marks on the cylinder head to match up for the purpose of checking valve timing. Valve timing can only be inspected by lining up the colored plates on the timing chain with the marks on the pulleys. It may be necessary to remove and reinstall the chain to match up the alignment marks Click here.

NEXT

OK
EGR valve is tightly closed.

CHECK WHETHER DTC OUTPUT RECURS (MISFIRE DTCS)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Clear the DTCs Click here.
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON.
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 or P0304.

Check the DTC judgment result.

Result
Result	Proceed to
NORMAL (DTC is not output)	A
ABNORMAL (DTC P0300, P0301, P0302, P0303 or P0304 is output)	B

END

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

CHECK INTAKE SYSTEM
1. Check the intake system for vacuum leaks Click here.
  
  OK
  
  No leaks in intake system.
  
  Tech Tips
  
  Perform "Inspection After Repair" after repairing or replacing the intake system Click here.
NG
REPAIR OR REPLACE INTAKE SYSTEM

OK

READ VALUE USING GTS (COOLANT TEMP)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Coolant Temp.

Read the Data List twice, when the engine is both cold and warmed up.

Standard

GTS Display	Condition	Specified Condition
Coolant Temp	Cold engine	Same as ambient air temperature
Coolant Temp	Warm engine	Between 75 and 100°C (167 and 212°F)

REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here

READ VALUE USING GTS (MAF)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF, Coolant Temp and Engine Speed.

Read MAF with the engine speed 3000 rpm.

Standard

GTS Display

Condition

Specified Condition

MAF

Shift lever position: N

A/C: off

Engine Speed: 3000 rpm

Between 4 gm/sec. and 10 gm/sec

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

PERFORM ACTIVE TEST USING GTS (CONTROL THE EGR STEP POSITION)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or more.

Tech Tips

The A/C switch and all accessory switches should be off.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position / All Data / MAP.

Check the engine idling condition and MAP values in the Data List while performing the Active Test.

Tech Tips

Do not leave the EGR valve open for 10 seconds or more during the Active Test.
Be sure to return the EGR valve to step 0 when the Active Test is completed.
Do not open the EGR valve 30 steps or more during the Active Test.

OK
MAP and idling condition change in response to EGR step position.

Standard

EGR Step Position (Active Test)

0 Steps

0 to 30 Steps

Idling condition

Steady idling

Idling changes from steady to rough idling or engine stalls

MAP

(Data List)

MAP value is 20 to 48 kPa(abs) [150 to 360 mmHg(abs)]

(EGR valve is fully closed)

MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed

Result
Result	Proceed to
NG	A
OK	B

Tech Tips

During Active Test, if the idling condition does not change in response to EGR step position, then there is probably a malfunction in the EGR valve.

INSPECT SPARK PLUG Click here

INSPECT EGR VALVE ASSEMBLY
1. Remove the EGR valve assembly Click here.
2. Check if the EGR valve is stuck open.
  
  OK
  
  EGR valve is tightly closed.
  
  Tech Tips
  
  Perform "Inspection After Repair" after replacing the EGR valve assembly Click here.
NG
REPLACE EGR VALVE ASSEMBLY Click here

OK
INSPECT SPARK PLUG
1. Inspect the spark plug of the misfiring cylinder Click here.
  
  Tech Tips
  
  Perform "Inspection After Repair" after replacing the spark plug Click here.
NG
REPLACE SPARK PLUG Click here

OK
CHECK FOR SPARKS (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.
  - Perform "Inspection After Repair" after repairing or replacing the ignition system Click here.
NEXT
CHECK CYLINDER COMPRESSION PRESSURE OF MISFIRING CYLINDER
1. Measure the cylinder compression pressure of the misfiring cylinder Click here.
  
  Tech Tips
  
  Perform "Inspection After Repair" after repairing or replacing the engine assembly Click here.
NG
CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

OK

CHECK TERMINAL VOLTAGE (POWER SOURCE OF FUEL INJECTOR ASSEMBLY)

Text in Illustration

*a
Front view of wire harness connector

(to ECM)

Disconnect the ECM connector.
Turn the ignition switch to ON.

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

Standard Voltage

Tester Connection	Condition	Specified Condition
B23-20 (#10) - B23-51 (E01)	Ignition switch ON	11 to 14 V
B23-17 (#20) - B23-51 (E01)	Ignition switch ON	11 to 14 V
B23-18 (#30) - B23-51 (E01)	Ignition switch ON	11 to 14 V
B23-19 (#40) - B23-51 (E01)	Ignition switch ON	11 to 14 V

CHECK FUEL INJECTOR CIRCUIT Click here

CHECK FUEL INJECTOR ASSEMBLY OF MISFIRING CYLINDER
1. Check the fuel injector assembly injection (whether fuel volume is high or low, and whether injection pattern is poor) Click here.
  
  Tech Tips
  
  Perform "Inspection After Repairs" after replacing the fuel injector assembly Click here.
NG
REPLACE FUEL INJECTOR ASSEMBLY Click here

OK
ADJUST VALVE TIMING

Tech Tips

There are no marks on the cylinder head to match up for the purpose of checking valve timing. Valve timing can only be inspected by lining up the colored plates on the timing chain with the marks on the pulleys. It may be necessary to remove and reinstall the chain to match up the alignment marks Click here.

NEXT

CHECK WHETHER DTC OUTPUT RECURS (MISFIRE DTCS)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Clear the DTCs Click here.
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON.
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 or P0304.

Check the DTC judgment result.

Result
Result	Proceed to
ABNORMAL (DTC P0300, P0301, P0302, P0303 or P0304 is output)	A
NORMAL (DTC is not output)	B

END

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

CHECK WHETHER DTC OUTPUT RECURS (MISFIRE DTCS)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Clear the DTCs Click here.
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON.
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 or P0304.

Check the DTC judgment result.

Result
Result	Proceed to
ABNORMAL (DTC P0300, P0301, P0302, P0303 or P0304 is output)	A
NORMAL (DTC is not output)	B

END

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

Disconnect the mass air flow meter sub-assembly connector.
Disconnect the ECM connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
B72-3 (VG) - B23-91 (VG)	Always	Below 1 Ω
B72-2 (E2G) - B23-92 (E2G)	Always	Below 1 Ω
B72-3 (VG) or B23-91 (VG) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE MASS AIR FLOW METER SUB-ASSEMBLY
1. Replace the mass air flow meter sub-assembly Click here.
  Tech Tips
  - If the results of the inspections performed in steps 13 and 20 indicated no problem, proceed to the next step without replacing the mass air flow meter sub-assembly.
  - Perform "Inspection After Repairs" after replacing the mass air flow meter sub-assembly Click here.
NEXT

CHECK WHETHER DTC OUTPUT RECURS (MISFIRE DTCS)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Clear the DTCs Click here.
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON.
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 or P0304.

Check the DTC judgment result.

Result
Result	Proceed to
ABNORMAL (DTC P0300, P0301, P0302, P0303 or P0304 is output)	A
NORMAL (DTC is not output)	B

REPLACE ECM Click here

END

CHECK FUEL LINE
1. Check the fuel lines for leaks or blockage.
  
  Tech Tips
  
  Perform "Inspection After Repair" after replacing the fuel pump Click here.
OK
REPLACE FUEL PUMP Click here

NG
REPAIR OR REPLACE FUEL LINE