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

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

DESCRIPTION

When a misfire occurs in the engine, hydrocarbons (HC) enter the exhaust gas in high concentrations. If this HC concentration is high enough, there could be an increase in exhaust emission levels. High concentrations of HC can also cause the temperature of the Three-Way Catalytic Converter (TWC) to increase, possibly damaging the TWC. To prevent this increase in emissions and limit the possibility of thermal damage, the ECM monitors the misfire rate. When the temperature of the TWC 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 misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. The misfire counter increments when the crankshaft rotation speed variations exceed the threshold values.

If the misfiring rate exceeds the threshold and could cause emission deterioration, the ECM illuminates the MIL.

Tip:

  • The ECM monitors misfires, which could cause emission deterioration, every 1000 crankshaft revolutions. When emission deterioration misfires are detected, the ECM illuminates the MIL and stores a DTC.

  • The ECM monitors misfires, which could damage the TWC, every 200 crankshaft revolutions. If TWC damaging misfires are detected, the ECM flashes the MIL and stores a DTC (2 trip detection logic).

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

P0300

Random / Multiple Cylinder Misfire Detected

Misfiring of random cylinders is detected (2 trip detection logic)

  • Open or short in engine wire harness

  • Connector connection

  • Ignition system

  • Fuel injector assembly

  • Fuel pressure

  • Manifold absolute pressure sensor

  • Engine coolant temperature sensor

  • Compression pressure

  • Valve clearance

  • Valve timing

  • ECM

Comes on/Blinks*

*: The MIL flashes when a catalyst-damaging misfire is detected.

DTC stored (Euro-OBD)

- (except Euro-OBD)

P0301

Cylinder 1 Misfire Detected

Misfiring of each cylinder is detected (2 trip detection logic)

  • Open or short in engine wire harness

  • Connector connection

  • Ignition system

  • Fuel injector assembly

  • Fuel pressure

  • Manifold absolute pressure sensor

  • Engine coolant temperature sensor

  • Compression pressure

  • Valve clearance

  • Valve timing

  • ECM

Comes on/Blinks*

*: The MIL flashes when a catalyst-damaging misfire is detected.

DTC stored (Euro-OBD)

- (except Euro-OBD)

P0302

Cylinder 2 Misfire Detected

Misfiring of each cylinder is detected (2 trip detection logic)

  • Open or short in engine wire harness

  • Connector connection

  • Ignition system

  • Fuel injector assembly

  • Fuel pressure

  • Manifold absolute pressure sensor

  • Engine coolant temperature sensor

  • Compression pressure

  • Valve clearance

  • Valve timing

  • ECM

Comes on/Blinks*

*: The MIL flashes when a catalyst-damaging misfire is detected.

DTC stored (Euro-OBD)

- (except Euro-OBD)

P0303

Cylinder 3 Misfire Detected

Misfiring of each cylinder is detected (2 trip detection logic)

  • Open or short in engine wire harness

  • Connector connection

  • Ignition system

  • Fuel injector assembly

  • Fuel pressure

  • Manifold absolute pressure sensor

  • Engine coolant temperature sensor

  • Compression pressure

  • Valve clearance

  • Valve timing

  • ECM

Comes on/Blinks*

*: The MIL flashes when a catalyst-damaging misfire is detected.

DTC stored (Euro-OBD)

- (except Euro-OBD)
Tip:

These DTCs are detected when the engine idles for approximately 10 minutes after warm-up. (Misfire can be clearly checked by activating the air conditioning system.)

WIRING DIAGRAM

Refer to DTC P0261 for fuel injector circuit.

Click here

CONFIRMATION DRIVING PATTERN

  1. Connect the GTS to the DLC3.

  2. Turn the ignition switch to ON.

  3. Turn the GTS on.

  4. Record DTCs and freeze frame data.

  5. Clear the DTCs (even if no DTCs are stored, perform the clear DTC operation).

    Click here

  6. Read the misfire counts of each cylinder (Cylinder #1 Misfire Count to Cylinder #3 Misfire Count) with the engine in an idling condition. If any misfire count is displayed, skip the following confirmation driving pattern.

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

    Tip:

    In order to store misfire DTCs, it is necessary to drive the vehicle for the period of time shown in the table below, with the engine speed and engine load the same as Misfire RPM in the freeze frame data.

    Engine Speed (rpm)

    Duration

    Idling

    10 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 for DTCs and freeze frame data.

  9. Record the DTC(s), freeze frame data and misfire counts.

  10. Turn the ignition switch off and wait for at least 30 seconds.

  11. Clear the DTCs (even if no DTCs are stored, perform the clear DTC operation).

    Click here

CAUTION / NOTICE / HINT

Note:

After replacing the ECM, perform idle learning.

Click here

Tip:

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

  • Read freeze frame data using the GTS. 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 duplicated, one of the following factors is considered to be a possible cause of the problem:

    1. The fuel level is low.

    2. Improper fuel is 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 each cylinder (#1 Misfire Count to Cylinder #3 Misfire Count).

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

  • When either Short FT #1 or Long FT #1 in the freeze frame data is outside the range of +/-25%, the air fuel ratio may be rich (-25% or less) or lean (+25% or more).

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

  • An extremely imbalanced drive wheel which causes body vibration may cause misfire DTCs to be stored.

PROCEDURE

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

    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 / Trouble Codes.

    5. Read the DTCs.

      Powertrain > Engine and ECT > Trouble Codes

      Result

      Result

      Proceed to

      DTC P0300, P0301, P0302 or P0303 is output

      A

      DTC P0300, P0301, P0302 or P0303 and other DTCs are output

      B
      Tip:

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

    B

    GO TO DTC CHART

    Click here

    A

  2. READ VALUE USING GTS (MISFIRE RPM)

    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 / All Data / Misfire RPM.

      Powertrain > Engine and ECT > Data List

      Tester Display

      Misfire RPM

    5. Read and note the Misfire RPM values.

      Tip:

      The Misfire RPM values indicate the vehicle conditions under which the misfire occurred.

    Result

    Proceed to

    NEXT
    NEXT

  3. CHECK PCV HOSE CONNECTIONS

    1. Check the PCV hose connections.

      Click here

      OK

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

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE PCV HOSE

    OK

  4. READ VALUE USING GTS (CYLINDER MISFIRE COUNT)

    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 / All Data / Cylinder #1 Misfire Count, Cylinder #2 Misfire Count, Cylinder #3 Misfire Count.

      Powertrain > Engine and ECT > Data List

      Tester Display

      Cylinder #1 Misfire Count

      Cylinder #2 Misfire Count

      Cylinder #3 Misfire Count

    5. Start the engine and allow the engine to idle.

    6. Read each value for Cylinder #1 Misfire Count to Cylinder #3 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.

    7. 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].

    8. Read the Cylinder #1 Misfire Count to Cylinder #3 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
      Tip:

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

    B

    CHECK INTAKE SYSTEMClick here

    A

  5. INSPECT SPARK PLUG

    1. Inspect the spark plug of the misfiring cylinder.

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE SPARK PLUG

    Click here

    OK

  6. CHECK FOR SPARKS (SPARK TEST)

    1. Perform a spark test.

      Click here

      Tip:

      If the result of the spark test is normal, proceed to the next step.

    Result

    Proceed to

    NEXT
    NEXT

  7. CHECK CYLINDER COMPRESSION PRESSURE

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

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

    OK

  8. CHECK TERMINAL VOLTAGE (POWER SOURCE OF FUEL INJECTOR ASSEMBLY)

    A200903C13

    *a

    Front view of wire harness connector

    (to Fuel Injector Assembly)

    1. Disconnect the fuel injector assembly connectors.

    2. Turn the ignition switch to ON.

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      B9-1 - Body ground

      Ignition switch ON

      11 to 14 V

      B11-1 - Body ground

      Ignition switch ON

      11 to 14 V

      B13-1 - Body ground

      Ignition switch ON

      11 to 14 V

    Result

    Proceed to

    OK

    NG
    NG

    CHECK FUEL INJECTOR CIRCUIT

    Click here

    OK

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

    1. Disconnect the fuel injector assembly connectors.

    2. Disconnect the ECM connector.

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

    Standard Resistance

    Tester Connection

    Condition

    Specified Condition

    B9-2 - B31-23 (#1)

    Always

    Below 1 Ω

    B11-2 - B31-20 (#2)

    Always

    Below 1 Ω

    B13-2 - B31-21 (#3)

    Always

    Below 1 Ω

    B9-2 or B31-23 (#1) - Body ground

    Always

    10 kΩ or higher

    B11-2 or B31-20 (#2) - Body ground

    Always

    10 kΩ or higher

    B13-2 or B31-21 (#3) - Body ground

    Always

    10 kΩ or higher

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  10. 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

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE FUEL INJECTOR ASSEMBLY

    Click here

    OK

  11. CHECK INTAKE SYSTEM

    1. Check the intake system for vacuum leaks.

      Click here

      OK

      No leaks from intake system.

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE INTAKE SYSTEM

    OK

  12. CHECK FUEL PRESSURE

    1. Check the fuel pressure.

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    CHECK AND REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE AND FILTER

    OK

  13. READ VALUE USING GTS (COOLANT TEMP)

    Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE ENGINE COOLANT TEMPERATURE SENSOR

    Click here

    OK

  14. INSPECT MANIFOLD ABSOLUTE PRESSURE SENSOR

    1. Inspect the manifold absolute pressure sensor.

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR

    Click here

    OK

  15. CHECK VALVE CLEARANCE OF MISFIRING CYLINDER

    1. Check the valve clearance of the misfiring cylinder.

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    ADJUST VALVE CLEARANCE

    Click here

    OK

  16. CHECK VALVE TIMING

    Click here

    Result

    Proceed to

    OK

    NG
    OK

    REPLACE ECM

    Click here

    NG

    CHECK ENGINE MECHANICAL SYSTEMClick here

  17. CHECK INTAKE SYSTEM

    1. Check the intake system for vacuum leaks.

      Click here

      OK

      No leaks from intake system.

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE INTAKE SYSTEM

    OK

  18. CHECK FUEL PRESSURE

    1. Check the fuel pressure.

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    CHECK AND REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE AND FILTER

    OK

  19. READ VALUE USING GTS (COOLANT TEMP)

    Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE ENGINE COOLANT TEMPERATURE SENSOR

    Click here

    OK

  20. INSPECT MANIFOLD ABSOLUTE PRESSURE SENSOR

    1. Inspect the manifold absolute pressure sensor.

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR

    Click here

    OK

  21. INSPECT SPARK PLUG

    1. Inspect the spark plug of the misfiring cylinder.

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE SPARK PLUG

    Click here

    OK

  22. CHECK FOR SPARKS (SPARK TEST)

    1. Perform a spark test.

      Click here

      Tip:

      If the result of the spark test is normal, proceed to the next step.

    Result

    Proceed to

    NEXT
    NEXT

  23. CHECK CYLINDER COMPRESSION PRESSURE

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

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

    OK

  24. CHECK TERMINAL VOLTAGE (POWER SOURCE OF FUEL INJECTOR ASSEMBLY)

    A200903C13

    *a

    Front view of wire harness connector

    (to Fuel Injector Assembly)

    1. Disconnect the fuel injector assembly connectors.

    2. Turn the ignition switch to ON.

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      B9-1 - Body ground

      Ignition switch ON

      11 to 14 V

      B11-1 - Body ground

      Ignition switch ON

      11 to 14 V

      B13-1 - Body ground

      Ignition switch ON

      11 to 14 V

    Result

    Proceed to

    OK

    NG
    NG

    CHECK FUEL INJECTOR CIRCUIT

    Click here

    OK

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

    1. Disconnect the fuel injector assembly connectors.

    2. Disconnect the ECM connector.

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

    Standard Resistance

    Tester Connection

    Condition

    Specified Condition

    B9-2 - B31-23 (#1)

    Always

    Below 1 Ω

    B11-2 - B31-20 (#2)

    Always

    Below 1 Ω

    B13-2 - B31-21 (#3)

    Always

    Below 1 Ω

    B9-2 or B31-23 (#1) - Body ground

    Always

    10 kΩ or higher

    B11-2 or B31-20 (#2) - Body ground

    Always

    10 kΩ or higher

    B13-2 or B31-21 (#3) - Body ground

    Always

    10 kΩ or higher

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  26. 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

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE FUEL INJECTOR ASSEMBLY

    Click here

    OK

  27. CHECK VALVE CLEARANCE OF MISFIRING CYLINDER

    1. Check the valve clearance of the misfiring cylinder.

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    ADJUST VALVE CLEARANCE

    Click here

    OK

  28. CHECK VALVE TIMING

    Click here

    Result

    Proceed to

    OK

    NG
    OK

    REPLACE ECM

    Click here

    NG

  29. CHECK ENGINE MECHANICAL SYSTEM

    1. Check for mechanical malfunctions that affect the valve timing, such as a jumped tooth or stretching of the timing chain.

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE MALFUNCTIONING PARTS, COMPONENT AND AREA

    OK

  30. CHECK WHETHER DTC OUTPUT RECURS (MISFIRE DTC)

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs.

      Powertrain > Engine and ECT > Clear DTCs

    5. Turn the ignition switch off and wait for at least 30 seconds.

    6. Start the engine and warm it up.

    7. Turn the GTS on.

    8. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

    9. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

    10. Read the pending DTCs.

      Powertrain > Engine and ECT > Trouble Codes

      Result

      Result

      Proceed to

      DTC P0300, P0301, P0302 or P0303 is output

      A

      DTCs are not output

      B
    A

    REPLACE ECM

    Click here

    B

    END