Diagnostic Procedure

DTC P0300 DIAGNOSTIC PROCEDURE TABLE

STEP	INSPECTION		ACTION
1	VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED Have FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS (Misfire related) been recorded?	Yes	Go to the next step.
1		No	Record the FREEZE FRAME 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.
2		No	Go to the next step.
3	VERIFY RELATED PENDING CODE OR STORED DTC Turn the ignition switch off then to the ON position (Engine off). Verify related pending code or stored DTCs. Are other DTCs present?	Yes	Go to the appropriate DTC troubleshooting. (See DTC TABLE .)
3		No	Go to the next step.
4	VERIFY CURRENT INPUT SIGNAL STATUS (KEY TO ON/IDLE) Access APP1, APP2, ECT, IAT, MAF, RPM, TP, and VSS PIDs using WDS or equivalent. (See PCM INSPECTION .) Is there any signal that is far out of specification when the ignition switch is turned to the ON position and the engine idles?	Yes	Inspect suspected circuit and/or part according to inspection results. (See PCM INSPECTION .) Then go to Step 20.
4		No	Go to the next step.
5	VERIFY CURRENT INPUT SIGNAL STATUS UNDER TROUBLE CONDITION Inspect the same PIDs as in Step 4 while simulating FREEZE FRAME DATA condition. Is there any signal which causes drastic changes?	Yes	Inspect suspected circuit and/or part according to inspection results. (See PCM INSPECTION .) Then go to Step 20.
5		No	Go to the next step.
6	INSPECT CMP SENSOR Inspect CMP sensor. (See CAMSHAFT POSITION (CMP) SENSOR INSPECTION .) Is CMP sensor normal?	Yes	Go to the next step.
6		No	Inspect installation condition and damages on timing chain and gears, repair the malfunctioning part. If it is normal, replace the CMP sensor. (See CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION .) Then go to Step 20.
7	VERIFY CKP SENSOR INSTALLATION CONDITION Inspect for CKP sensor looseness. Is CKP sensor loosen?	Yes	Retighten the CKP sensor, then go to Step.
7		No	Go to the next step.
8	INSPECT IGNITION COIL HARNESSES Inspect the ignition coil related harness condition (intermittent open or short) for all cylinders. Are harness conditions normal?	Yes	Go to the next step.
8		No	Repair suspected wiring harnesses, then go to Step 20.
9	INSPECT IGNITION SYSTEM OPERATION Carry out spark test. (See SPARK TEST ) Is strong blue spark visible at each cylinder?	Yes	Go to the next step.
9		No	Repair or replace malfunctioning part according to spark test result. Then go to Step 20.
10	INSPECT MAF PID Start the engine. Access MAF PID using the WDS or equivalent. Race the engine and verify that MAF PID changes quickly according to change in the engine speed. Is MAF PID response normal?	Yes	Go to the next step.
10		No	Replace the MAF sensor, then go to Step 20. (See MASS AIR FLOW (MAF)/INTAKE AIR TEMPERATURE (IAT) SENSOR REMOVAL/INSTALLATION .)
11	INSPECT EXCESSIVE AIR SUCTION IN INTAKE AIR SYSTEM Inspect for air leakage at following: Between the MAF sensor and throttle body Between throttle body and intake manifold Is there any malfunction?	Yes	Repair or replace suspected part, then go to Step 20.
11		No	Go to the next step.
12	INSPECT FUEL LINE PRESSURE Inspect fuel line pressure. (See FUEL LINE PRESSURE INSPECTION .) Is fuel line pressure normal?	Yes	Go to Step 14.
12		No	If the fuel line pressure is too low, go to the next step. If the fuel line pressure is excess high, replace the fuel pump unit, then go to Step 20. (See FUEL PUMP UNIT REMOVAL/INSTALLATION .)
13	INSPECT FUEL LINE FROM FUEL PUMP TO FUEL DELIVERY PIPE Visually inspect fuel line for fuel leakage. Is there any fuel leakage?	Yes	Replace suspected fuel line, then go to Step 20.
13		No	Inspect fuel filters for following: Foreign materials or stain inside fuel filter (low-pressure side) Perform following actions depend on the result above. If foreign materials or stain is found inside fuel filter (low-pressure side), clean the fuel tank and filter (low-pressure side). If normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION .) Then, go to Step 20.
14	INSPECT ENGINE COMPRESSION Inspect engine compression. (See COMPRESSION INSPECTION .) Is it normal?	Yes	Go to the next step.
14		No	Perform engine overhaul for repairs, then go to Step 20.
15	INSPECT VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION Inspect variable valve timing control system operation. (See VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION INSPECTION .) Does variable valve timing control system work properly?	Yes	Go to the next step.
15		No	Repair or replace malfunctioning part according to variable valve timing control system inspection results, then go to Step 20.
16	INSPECT OPERATION OF PURGE CONTROL SOLENOID VALVE Turn the ignition switch off. Connect the vacuum pump to purge control solenoid valve and apply vacuum to solenoid. Verify that solenoid holds vacuum. Turn the ignition switch to the ON position (Engine off). Access EVAPCP PID in SIMULATION TEST using the WDS or equivalent. Set duty value to 100% for EVAPCP PID. Apply vacuum while turning solenoid from OFF to ON and simulating EVAPCP PID with 100% duty value. Verify that solenoid releases vacuum while solenoid is turned ON. Is purge control solenoid valve operation normal?	Yes	Go to the next step.
16		No	Replace the purge control solenoid valve, then go to Step 20. (See PURGE SOLENOID VALVE REMOVAL/INSTALLATION .)
17	INSPECT PCV VALVE OPERATION Turn the ignition switch off. Remove PCV valve and inspect valve operation. (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION .) Is PCV valve operation normal?	Yes	Replace the PCV valve, then go to Step 20.
17		No	Go to the next step.
18	INSPECT OPERATION OF EGR VALVE Remove the EGR valve. Visually inspect the EGR valve for stuck to open. Is EGR valve stuck to open?	Yes	Repair or replace the EGR valve, then go to Step 20. (See EGR VALVE REMOVAL/INSTALLATION .)
18		No	Go to the next step.
19	INSPECT SEALING OF ENGINE COOLANT PASSAGE Perform "ENGINE COOLANT LEAKAGE INSPECTION." (See ENGINE COOLANT LEAKAGE INSPECTION .) Is there any malfunction?	Yes	Repair or replace malfunctioning part according to inspection results. Then go to the next step.
19		No	Go to the next step.
20	VERIFY TROUBLESHOOTING OF MISFIRE DTC COMPLETED Make sure to reconnect all disconnected connectors. Turn the ignition switch to the ON position (Engine off). Clear the DTC from the memory using the WDS or equivalent. Perform the KOER self-test (using WDS or equivalent) or the HO2S heater, HO2S, and TWC Repair Verification Drive Mode (not using WDS or equivalent). (See KOEO/KOER SELF TEST .) (See OBD-II DRIVE MODE .) Is the PENDING CODE for this DTC present?	Yes	Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION .)
20		No	Go to the next step.
21	VERIFY AFTER REPAIR PROCEDURE Perform the "AFTER REPAIR PROCEDURE". (See AFTER REPAIR PROCEDURE .) Are any DTC present?	Yes	Go to the applicable DTC troubleshooting. (See DTC TABLE .)
21		No	Troubleshooting completed.