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

A01DR45E01
Text in Illustration
*1 Camshaft Position Sensor
*2 Crankshaft Position Sensor
*3 ECM

When the engine misfires, high concentrations of hydrocarbons enter the exhaust gas. Extremely high hydrocarbon 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 rate. 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 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 rate exceeds the threshold level and could cause emission deterioration, the ECM illuminates the MIL and stores a DTC.

DTC No. DTC Detection Condition Trouble Area
P0300

Simultaneous misfiring of several cylinders occurs and one of the following conditions below is detected (2 trip detection logic):


  • A high temperature misfire occurs in 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

  • Mass air flow meter

  • Engine coolant temperature sensor

  • Compression pressure

  • Valve timing

  • PCV valve and hose

  • PCV hose connection

  • Intake system

  • ECM

P0301

P0302

P0303

P0304

Misfiring of a specific cylinder occurs and one of the following conditions below is detected (2 trip detection logic):


  • A high temperature misfire occurs in 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.

WIRING DIAGRAM

A01DN70E01

CONFIRMATION DRIVING PATTERN


  1. Connect the intelligent tester to the DLC3.

  2. Turn the ignition switch to ON.

  3. Turn the tester on.

  4. Record the DTC(s) and freeze frame data.

  5. Using the tester, switch the ECM from normal mode to check mode Click here.

  6. Read the misfire count of each cylinder (Cylinder #1 to #4) with the engine idling. If any misfire count is displayed, skip the following confirmation driving pattern.

  7. If no misfire counts are displayed, drive the vehicle several times at the engine speed and engine load recorded in the freeze frame data.

    Tech Tips


    • In order to detect misfire DTCs, drive the vehicle at the engine speed and engine load recorded in the freeze frame data for the time specified in the table below.

    Engine Speed Duration
    Idling 8 minutes or more
    1000 4 minutes 30 seconds or more
    2000 2 minutes 30 seconds or more
    3000 1 minute 30 seconds or more

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

    Tech Tips

    Do not turn the ignition switch off until the stored DTCs and freeze frame data have been recorded. When the ECM returns to normal mode (default), the stored DTCs, freeze frame data and other data are cleared.

  9. Record the DTCs, freeze frame data and misfire count.

  10. Turn the ignition switch off and wait for at least 5 seconds.

INSPECTION PROCEDURE

Tech Tips


  • If any DTCs other than misfire DTCs are output, troubleshoot those DTCs first.

  • Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. 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 freeze frame data.

  • If the misfire still cannot be reproduced even though the conditions stored in the freeze frame data have been reproduced, one of the following factors can be considered to be a possible cause of the problem:


    1. The fuel level is low.

    2. Improper fuel was used.

    3. The spark plugs are dirty.

    4. The problem is complex and involves multiple factors.

  • After finishing repairs, check that no misfire occurs in any cylinder (Cylinder #1, #2, #3 and #4).

  • Be sure to confirm that no misfiring cylinder DTCs are stored again by conducting the confirmation driving pattern after the repairs.

  • When either Short FT #1 or Long FT #1 values in the freeze frame data are not within 20% of the central value, the air fuel ratio may be rich (-20% or less) or lean (+20% or more).

  • When the Coolant Temp in the freeze frame data is below 75°C (167°F), the misfires occurred only while warming up the engine.

PROCEDURE


  1. CHECK FOR ANY OTHER DTCS OUTPUT (IN ADDITION TO MISFIRE CODES)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / DTC.

    5. Read the DTCs.

      Result
      Result Proceed to
      DTC P0300, P0301, P0302, P0303 and/or P0304 is 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.


    B

    GO TO DTC CHART Click here

    A

  2. READ VALUE USING INTELLIGENT TESTER (MISFIRE RPM AND MISFIRE LOAD)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON and turn the tester on.

    3. Enter the following menus: Powertrain / Engine and ECT / Data List / Misfire RPM and Misfire Load.

    4. 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

  3. CHECK PCV HOSE CONNECTIONS


    1. Check the PCV hose connections Click here.

      OK
      PCV hose is correctly connected and is not damaged.

    NG

    REPAIR OR REPLACE PCV HOSE

    OK

  4. READ VALUE USING INTELLIGENT TESTER


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / Cylinder #1 (to #4) Misfire Count.

    5. Drive the vehicle at the engine speed and engine load noted in the "Read Value Using Intelligent Tester (Misfire RPM and Misfire Load)" procedure above.

    6. Read Cylinder #1 (to #4) Misfire Count or the DTCs displayed on the tester.

      Result
      Misfire Count or DTC Result Proceed to
      Most misfires occur in only 1 or 2 cylinders, or misfire DTCs for only 1 or 2 cylinders are output A
      3 cylinders or more have equal misfire counts, or misfire DTCs for 3 or more cylinders are output 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's record of the engine coolant temperature is below 75°C (167°F), the misfire may be detected only when the engine is cold.

      • If the freeze frame data's record of the Engine Run Time is below 120 seconds, the misfire may be detected immediately after the engine is started.


    B

    CHECK INTAKE SYSTEM Click here

    A

  5. CHECK SPARK PLUG


    1. Check the spark plug of the misfiring cylinder Click here.


    NG

    REPLACE SPARK PLUG Click here

    OK

  6. CHECK FOR SPARK AND IGNITION


    1. Perform a spark test Click here.


    NG

    REPLACE SPARK PLUG WITH NORMAL ONE AND CHECK SPARK OF MISFIRING CYLINDER Click here

    OK

  7. CHECK CYLINDER COMPRESSION PRESSURE OF MISFIRING CYLINDER


    1. Measure the cylinder compression pressure of the misfiring cylinder Click here.


    NG

    CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

    OK

  8. CHECK FUEL INJECTOR ASSEMBLY (POWER SOURCE)


    1. A01DN3LE03
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Fuel Injector Assembly)

      Disconnect the fuel injector assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      C50-2 - Body ground Ignition switch ON 11 to 14 V
      C2-2 - Body ground Ignition switch ON 11 to 14 V
      C51-2 - Body ground Ignition switch ON 11 to 14 V
      C4-2 - Body ground Ignition switch ON 11 to 14 V

    3. Reconnect the fuel injector assembly connector.


    NG

    CHECK FUEL INJECTOR CIRCUIT Click here

    OK

  9. CHECK HARNESS AND CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)


    1. Disconnect the fuel injector assembly connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      C50-1 - C64-6 (#10) Always Below 1 Ω
      C2-1 - C64-7 (#20) Always Below 1 Ω
      C51-1 - C64-8 (#30) Always Below 1 Ω
      C4-1 - C64-9 (#40) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      C50-1 or C64-6 (#10) - Body ground Always 10 kΩ or higher
      C2-1 or C64-7 (#20) - Body ground Always 10 kΩ or higher
      C51-1 or C64-8 (#30) - Body ground Always 10 kΩ or higher
      C4-1 or C64-9 (#40) - Body ground Always 10 kΩ or higher

    4. Reconnect the fuel injector assembly connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)

    OK

  10. INSPECT ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, #30 AND/OR #40 VOLTAGE)

    A01DU49E20
    Text in Illustration
    *a

    Component with harness connected

    (ECM)

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      C64-6 (#10) - C64-11 (E01) Ignition switch ON 11 to 14 V
      C64-7 (#20) - C64-11 (E01) Ignition switch ON 11 to 14 V
      C64-8 (#30) - C64-11 (E01) Ignition switch ON 11 to 14 V
      C64-9 (#40) - C64-11 (E01) Ignition switch ON 11 to 14 V

    NG

    CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND) Click here

    OK

  11. CHECK FUEL INJECTOR OF MISFIRING CYLINDER


    1. Check the fuel injector injection (whether fuel volume is high or low, and whether injection pattern is poor) Click here.


    NG

    REPLACE FUEL INJECTOR ASSEMBLY Click here

    OK

  12. CHECK INTAKE SYSTEM


    1. Check the intake system for vacuum leakage Click here.

      OK
      No leakage from intake system.

    NG

    REPAIR OR REPLACE INTAKE SYSTEM

    OK

  13. CHECK FUEL PRESSURE


    1. Check the fuel pressure Click here.


    NG

    CHECK FUEL LINE Click here

    OK

  14. READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.

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

      Standard
      With cold engine
      Same as ambient air temperature.
      With warm engine
      Between 75°C and 95°C (167°F and 203°F).

    NG

    REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here

    OK

  15. INSPECT MASS AIR FLOW METER


    1. Inspect the mass air flow meter Click here.


    NG

    REPLACE MASS AIR FLOW METER Click here

    OK

  16. CHECK ENGINE MECHANICAL SYSTEM

    Tech Tips

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


    NEXT

  17. CHECK WHETHER DTC OUTPUT RECURS (DTC P0300, P0301, P0302, P0303 AND/OR P0304)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Clear the DTCs Click here.

    5. Start the engine and warm it up.

    6. Switch the ECM from normal mode to check mode using the tester.

    7. Run the engine at an engine speed of 1000 rpm for 3 minutes.

    8. Enter the following menus: Powertrain / Engine and ECT / DTC.

    9. Read the DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTC P0300, P0301, P0302, P0303 and/or P0304 is output B

    B

    REPLACE ECM Click here

    A

    SYSTEM IS OK

  18. CHECK INTAKE SYSTEM


    1. Check the intake system for vacuum leakage Click here.

      OK
      No leakage from intake system.

    NG

    REPAIR OR REPLACE INTAKE SYSTEM

    OK

  19. CHECK FUEL PRESSURE


    1. Check the fuel pressure Click here.


    NG

    CHECK FUEL LINE Click here

    OK

  20. READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.

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

      Standard
      With cold engine
      Same as ambient air temperature.
      With warm engine
      Between 75°C and 95°C (167°F and 203°F).

    NG

    REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here

    OK

  21. INSPECT MASS AIR FLOW METER


    1. Inspect the mass air flow meter Click here.


    NG

    REPLACE MASS AIR FLOW METER Click here

    OK

  22. CHECK ENGINE MECHANICAL SYSTEM

    Tech Tips

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


    NEXT

  23. CHECK WHETHER DTC OUTPUT RECURS (DTC P0300, P0301, P0302, P0303 AND/OR P0304)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Clear the DTCs Click here.

    5. Start the engine and warm it up.

    6. Switch the ECM from normal mode to check mode using the tester.

    7. Run the engine at an engine speed of 1000 rpm for 3 minutes.

    8. Enter the following menus: Powertrain / Engine and ECT / DTC.

    9. Read the DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTC P0300, P0301, P0302, P0303 and/or P0304 is output B

    B

    CHECK SPARK PLUG Click here

    A

    SYSTEM IS OK

  24. CHECK SPARK PLUG


    1. Check the spark plug of the misfiring cylinder Click here.


    NG

    REPLACE SPARK PLUG Click here

    OK

  25. CHECK FOR SPARK AND IGNITION (SPARK TEST)


    1. Perform a spark test Click here.


    NG

    REPLACE SPARK PLUG WITH NORMAL ONE AND CHECK SPARK OF MISFIRING CYLINDER Click here

    OK

  26. CHECK CYLINDER COMPRESSION PRESSURE OF MISFIRING CYLINDER


    1. Measure the cylinder compression pressure of the misfiring cylinder Click here.


    NG

    CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

    OK

  27. CHECK FUEL INJECTOR ASSEMBLY (POWER SOURCE)


    1. A01DN3LE03
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Fuel Injector Assembly)

      Disconnect the fuel injector assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      C50-2 - Body ground Ignition switch ON 11 to 14 V
      C2-2 - Body ground Ignition switch ON 11 to 14 V
      C51-2 - Body ground Ignition switch ON 11 to 14 V
      C4-2 - Body ground Ignition switch ON 11 to 14 V

    3. Reconnect the fuel injector assembly connector.


    NG

    CHECK FUEL INJECTOR CIRCUIT Click here

    OK

  28. CHECK HARNESS AND CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)


    1. Disconnect the fuel injector assembly connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      C50-1 - C64-6 (#10) Always Below 1 Ω
      C2-1 - C64-7 (#20) Always Below 1 Ω
      C51-1 - C64-8 (#30) Always Below 1 Ω
      C4-1 - C64-9 (#40) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      C50-1 or C64-6 (#10) - Body ground Always 10 kΩ or higher
      C2-1 or C64-7 (#20) - Body ground Always 10 kΩ or higher
      C51-1 or C64-8 (#30) - Body ground Always 10 kΩ or higher
      C4-1 or C64-9 (#40) - Body ground Always 10 kΩ or higher

    4. Reconnect the fuel injector assembly connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)

    OK

  29. INSPECT ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, #30 AND/OR #40 VOLTAGE)

    A01DU49E20
    Text in Illustration
    *a

    Component with harness connected

    (ECM)

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      C64-6 (#10) - C64-11 (E01) Ignition switch ON 11 to 14 V
      C64-7 (#20) - C64-11 (E01) Ignition switch ON 11 to 14 V
      C64-8 (#30) - C64-11 (E01) Ignition switch ON 11 to 14 V
      C64-9 (#40) - C64-11 (E01) Ignition switch ON 11 to 14 V

    NG

    CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND) Click here

    OK

  30. CHECK FUEL INJECTOR OF MISFIRING CYLINDER


    1. Check the fuel injector injection (whether fuel volume is high or low, and whether injection pattern is poor) Click here.


    NG

    REPLACE FUEL INJECTOR ASSEMBLY Click here

    OK

    REPLACE ECM Click here

  31. REPLACE SPARK PLUG WITH NORMAL ONE AND CHECK SPARK OF MISFIRING CYLINDER


    1. Replace the installed spark plug with a spark plug that functions normally.

    2. Perform a spark test.

      CAUTION:

      During the test, disconnect all the injector connectors.

      Note

      Do not crank the engine for more than 2 seconds.


      1. Install the spark plug to the ignition coil.

      2. Disconnect the 4 fuel injector connectors.

      3. Touch the spark plug assembly to the cylinder head.

      4. Crank the engine for less than 2 seconds and check for sparks.

        OK
        Sparks jump across electrode gap.

    NG

    REPLACE IGNITION COIL WITH NORMAL ONE AND CHECK SPARK OF MISFIRING CYLINDER Click here

    OK

    REPLACE SPARK PLUG Click here

  32. REPLACE IGNITION COIL WITH NORMAL ONE AND CHECK SPARK OF MISFIRING CYLINDER


    1. Replace the ignition coil with an ignition coil that functions normally.

    2. Perform a spark test.

      CAUTION:

      During the test, disconnect all the injector connectors.

      Note

      Do not crank the engine for more than 2 seconds.


      1. Install the spark plug to the ignition coil and connect the ignition coil connector.

      2. Disconnect the 4 fuel injector connectors.

      3. Touch the spark plug assembly to the cylinder head.

      4. Crank the engine for less than 2 seconds and check for sparks.

        OK
        Sparks jump across electrode gap.

    NG

    REPLACE ECM Click here

    OK

    REPLACE IGNITION COIL Click here

  33. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND)


    1. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      C64-11 (E01) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - BODY GROUND)

    OK

    REPLACE FUEL INJECTOR ASSEMBLY Click here

  34. CHECK FUEL LINE


    1. Check the fuel lines for leaks or blockage Click here.

      OK
      No leaks or blockage.
      Result
      Result Proceed to
      NG A
      OK (for 5 Door) B
      OK (for 3 Door) C

    B

    REPLACE FUEL PUMP Click here

    C

    REPLACE FUEL PUMP Click here

    A

    REPAIR OR REPLACE FUEL LINE