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DTC P0300:00

DTC P0300:00  Random misfire detected 
DETECTION CONDITION 
  • The PCM monitors CKP sensor input signal interval time. The PCM calculates the change of interval time for each cylinder. If the change of interval time exceeds the preprogrammed criteria, the PCM detects a misfire in the corresponding cylinder. While the engine is running, the PCM counts the number of misfires that occurred at 200 crankshaft revolutions and 1, 000 crankshaft revolutions  and calculates the misfire ratio for each crankshaft revolution. If the ratio exceeds the preprogrammed criteria, the PCM determines that a misfire, which can damage the catalytic converter or affect emission performance, has occurred.

Diagnostic support note 
  • This is a continuous monitor (misfire).
  • The MIL illuminates if the PCM detects the misfire which affects emission performance in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
  • The MIL flashes if the PCM detects a misfire which can damage the catalytic converter during the first drive cycle.
  • PENDING CODE is available if the PCM detects the misfire which affects emission performance during first drive cycle.
  • FREEZE FRAME DATA (Mode 2)/Snapshot data is available.
  • The DTC is stored in the PCM memory.
POSSIBLE CAUSE 
  • Erratic signal to PCM
    • APP sensor signal malfunction
    • ECT sensor No. 1 signal malfunction
    • IAT sensor signal malfunction
    • MAF sensor signal malfunction
    • CKP sensor signal malfunction
    • TP sensor signal malfunction
    • VSS signal malfunction
  • CMP sensor connector or terminals malfunction
  • CMP sensor malfunction
  • CKP sensor connector or terminals malfunction
  • CKP sensor malfunction
  • Ignition system malfunction
    • Spark plug malfunction
    • Ignition coil related wiring harness malfunction
    • Ignition coil malfunction
  • MAF sensor malfunction
  • Excessive air suction in intake air system (between MAF sensor and intake manifold)
  • Purge solenoid valve malfunction
  • Fuel supply system malfunction or improper fuel line pressure
    • Fuel leakage in fuel line
    • Fuel filter restricted
    • Fuel pressure regulator (built-into fuel pump unit) malfunction
    • Fuel runout
    • Fuel pump unit malfunction
  • Improper operation of variable valve timing control system
  • EGR valve malfunction
  • Engine malfunction
    • Insufficient engine compression
    • Engine coolant leakage
  • PCV valve malfunction
  • Poor quality fuel
  • PCM malfunction
DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 VERIFY FREEZE FRAME DATA (MODE 2)/SNAPSHOT DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED 
  • Have the FREEZE FRAME DATA (Mode 2)/snapshot data and DIAGNOSTIC MONITORING TEST RESULTS (misfire related) been recorded?
 Yes Go to the next step.
No Record the FREEZE FRAME DATA (Mode 2)/snapshot data and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
2 VERIFY RELATED REPAIR INFORMATION AVAILABILITY 
  • Verify related Service Bulletins and/or on-line repair information availability.
  • Is any related repair information available?
 Yes Perform repair or diagnosis according to the available repair information.
  • If the vehicle is not repaired, go to the next step.
No Go to the next step.
3 VERIFY RELATED PENDING CODE AND STORED DTC 
  • Switch the ignition to off, then to ON (engine off).
  • Perform the DTC Reading Procedure and Pending Trouble Code Access Procedure.

    (See ON-BOARD DIAGNOSTIC TEST ).

  • Are any other DTCs present?
 Yes Go to the applicable DTC inspection.
(See DTC TABLE ).
No Go to the next step.
4 VERIFY CURRENT INPUT SIGNAL STATUS 
  • Access the following PIDs using the M-MDS.

    (See ON-BOARD DIAGNOSTIC TEST ).

    • APP1
    • APP2
    • ECT
    • IAT
    • MAF
    • RPM
    • TP REL
    • VSS
  • Is there any signal that is far out of specification when switch the ignition to ON and the engine idles? (See PCM INSPECTION ).
 Yes Inspect the suspected sensor and related wiring harness. Repair or replace the malfunctioning part according to the inspection results, then go to Step 25.
No Go to the next step.
5 VERIFY CURRENT INPUT SIGNAL STATUS UNDER FREEZE FRAME DATA (MODE 2) CONDITION 
CAUTION:
  • While performing this step, always operate the vehicle in a safe and lawful manner.
  • When the M-MDS is used to observe monitor system status while driving, be sure to have another technician with you, or record the data in the M-MDS using the PID/DATA MONITOR AND RECORD capturing function and inspect later.

  • Access the following PIDs using the M-MDS under the FREEZE FRAME DATA (Mode 2) condition. (See ON-BOARD DIAGNOSTIC TEST ).
    • APP1
    • APP2
    • ECT
    • IAT
    • MAF
    • RPM
    • TP REL
    • VSS
  • Is there any signal which causes drastic changes?
 Yes Inspect the suspected sensor and related wiring harness. Repair or replace the malfunctioning part according to the inspection results, then go to Step 25.
No Go to the next step.
6 INSPECT CMP SENSOR CONNECTOR CONDITION 
  • Switch the ignition to off.
  • Disconnect the CMP sensor connector.
  • Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
  • Is there any malfunction?
 Yes Repair or replace the terminal and/or connector, then go to Step 25.
No Go to the next step.
7 INSPECT CMP SENSOR 
 Yes Replace the CMP sensor, then go to Step 25.
(See CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION ).
No Go to the next step.
8 INSPECT CKP SENSOR CONNECTOR CONDITION 
  • Disconnect the CKP sensor connector.
  • Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
  • Is there any malfunction?
 Yes Repair or replace the terminal and/or connector, then go to Step 25.
No Go to the next step.
9 INSPECT CKP SENSOR 
 Yes Replace the CKP sensor, then go to Step 25.
(See CRANKSHAFT POSITION (CKP) SENSOR REMOVAL/INSTALLATION ).
No Go to the next step.
10 INSPECT IGNITION SYSTEM OPERATION 
 Yes Go to Step 14.
No Go to the next step.
11 INSPECT SPARK PLUG 
 Yes Replace the spark plug, then go to Step 25.
(See SPARK PLUG REMOVAL/INSTALLATION ).
No Go to the next step.
12 INSPECT IGNITION COIL RELATED WIRING HARNESS 
  • Inspect the ignition coil related wiring harness condition (intermittent open or short) for all cylinders.
  • Is there any malfunction?
 Yes Repair or replace the malfunctioning wiring harness, then go to Step 25.
No Go to the next step.
13 INSPECT IGNITION COIL 
 Yes Replace the malfunctioning ignition coil, then go to Step 25.
(See IGNITION COIL REMOVAL/INSTALLATION ).
No Go to the next step.
14 VERIFY PID DATA FOR MAF SENSOR MALFUNCTION 
  • Access the MAF PID using the M-MDS.

    (See ON-BOARD DIAGNOSTIC TEST ).

  • Verify that the MAF PID value changes quickly while increasing (racing) the engine speed.
  • Is the MAF PID response normal?

    (See PCM INSPECTION ).

 Yes Go to Step 16.
No Go to the next step.
15 INSPECT INTAKE AIR SYSTEM FOR AIR SUCTION 
  • Inspect for air leakage between the following:
    • MAF sensor and throttle body
    • Throttle body and intake manifold
    NOTE:
    • Engine speed may change when rust penetrating agent is sprayed on the air suction area.
  • Is there any leakage?
 Yes Repair or replace the malfunctioning part according to the inspection results, then go to Step 25.
No Replace the MAF/IAT sensor, then go to Step 25.
(See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION ).
16 VERIFY SIMULATION ITEM FOR PURGE SOLENOID VALVE MALFUNCTION 
  • Switch the ignition to off.
  • Connect the vacuum pump to the purge solenoid valve and apply vacuum to the solenoid.
  • Verify that the solenoid holds vacuum.
  • Switch the ignition to ON (engine off).
  • Access the EVAPCP PID of simulation item using the M-MDS.

    (See ON-BOARD DIAGNOSTIC TEST ).

  • Set the purge solenoid value to 100 % for the EVAPCP PID.
  • Verify that the purge solenoid value releases vacuum while the 100 % for the EVPCP PID.
  • Is the purge solenoid valve operation normal?
 Yes Go to the next step.
No Replace the purge solenoid valve, then go to Step 25.
(See PURGE SOLENOID VALVE REMOVAL/INSTALLATION ).
17 INSPECT FUEL LINE PRESSURE 
  • Switch the ignition to off.
    NOTE:
    • If engine will not start, inspect fuel line pressure with ignition switches to ON.
  • Inspect fuel line pressure with engine is running.

    (See FUEL LINE PRESSURE INSPECTION ).

  • Is there any malfunction?
 Yes Go to the next step.
No Go to Step 20.
18 INSPECT FOR FUEL LINE LEAKAGE 
  • Visually inspect for leakage from fuel line.
  • Is there any leakage?
 Yes Repair or replace the malfunctioning part according to the inspection results, then go to Step 25.
No Go to the next step.
19 INSPECT FUEL FILTER 
  • Visually inspect for foreign materials or stain inside fuel filter.
  • Is there any foreign materials or stain?
 Yes Repair or replace the malfunctioning part according to the inspection results, then go to Step 25.
No Replace the fuel pump unit, then go to Step 25.
(See FUEL PUMP UNIT REMOVAL/INSTALLATION ).
20 INSPECT VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION 
 Yes Repair or replace the malfunctioning part according to the inspection results, then go to Step 25.
No Go to the next step.
21 INSPECT EGR VALVE 
 Yes Replace the EGR valve, then go to Step 25.
(See EGR VALVE REMOVAL/INSTALLATION ).
No Go to the next step.
22 INSPECT ENGINE COMPRESSION 
 Yes Repair or replace the malfunctioning parts according to the inspection results, then go to Step 25.
No Go to the next step.
23 INSPECT SEALING OF ENGINE COOLANT PASSAGE 
 Yes Repair or replace the malfunctioning part according to the inspection results, then go to Step 25.
No Go to the next step.
24 INSPECT PCV VALVE OPERATION 
 Yes Replace the PCV valve and the oil separator as a single unit, then go to the next step.
(See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION ).
No Poor quality fuel is used.
  • Replace the fuel, then go to the next step.
25 VERIFY DTC TROUBLESHOOTING COMPLETED 
  • Make sure to reconnect all disconnected connectors.
  • Clear the DTC from the PCM memory using the M-MDS.

    (See AFTER REPAIR PROCEDURE ).

  • Start the engine and warm it up completely.
  • Perform the Pending Trouble Code Access Procedure.

    (See ON-BOARD DIAGNOSTIC TEST ).

  • Is the PENDING CODE for this DTC present?
 Yes Repeat the inspection from Step 1.

Go to the next step.
No Go to the next step.
26 VERIFY AFTER REPAIR PROCEDURE 
 Yes Go to the applicable DTC inspection.
(See DTC TABLE ).
No DTC troubleshooting completed.
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