#
DTC P0301, P0302, P0303, P0304 [L8, LF, L3]

id0102a1806600

DTC P0301 DTC P0302 DTC P0303 DTC P0304 | Cylinder No.1 misfire detected Cylinder No.2 misfire detected Cylinder No.3 misfire detected Cylinder No.4 misfire detected
--- | ---
DETECTION CONDITION | • The PCM monitors the 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 the misfire which can damage the catalytic converter during first drive cycle. • PENDING CODE is available if the PCM detects the misfire which affects emission performance during first drive cycle. • FREEZE FRAME DATA is available. • DTC is stored in the PCM memory.
POSSIBLE CAUSE | • Spark plug malfunction • Ignition system malfunction • Fuel injector malfunction • Air suction in intake air system (between dynamic chamber and cylinder head) • Inadequate engine compression due to engine internal malfunction • Related connector or terminal malfunction • Related wiring harness malfunction

Diagnostic procedure

STEP | INSPECTION | ACTION
--- | --- | ---
1 | VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAS BEEN RECORDED • Has FREEZE FRAME DATA been recorded? | Yes | Go to the next step.
No | Record the FREEZE FRAME on the repair order, then go to the next step.
2 | VERIFY RELATED REPAIR INFORMATION AVAILABILITY • Verify related Service Information availability. • Is any related Service Information available? | Yes | Perform repair or diagnosis according to the available Service information. If the vehicle is not repaired, go to the next step.
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. • Is other DTCs present? | Yes | Go to the appropriate DTC troubleshooting. (See DTC TABLE [L8, LF, L3].)
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 the WDS or equivalent. (See PCM INSPECTION [L8, LF, L3].) • Is there any signal that is far out of specification when ignition switch is turned to the ON position and engine idles? | Yes | Inspect suspected circuit and/or part according to inspection results. Then go to Step 14. (See PCM INSPECTION [L8, LF, L3].)
No | Go to the next step.
5 | VERIFY CURRENT INPUT SIGNAL STATUS UNDER TROUBLE CONDITION • Inspect 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. Then go to Step 14. (See PCM INSPECTION [L8, LF, L3].)
No | Go to the next step.
6 | INSPECT SPARK PLUG CONDITION • Turn the ignition switch off. • Remove spark plug from suspected cylinder. • Inspect spark plug condition: - Cracks - Excess wear - Gap - Wet • Is any problem found on spark plug? | Yes | • If spark plug is wet, fuel flooding is suspected. Then go to Step 14. • If spark plug has a cracks, excessive wear or improper gap, replace the malfunctioning spark plug. Then go to Step 14.
No | Go to the next step.
7 | INSPECT IGNITION COIL HARNESSES • Inspect the ignition coil related harness condition (intermittent open or short) for suspected cylinder. • Are harness conditions normal? | Yes | Go to the next step.
No | Repair suspected wiring harnesses, then go to Step 14.
8 | INSPECT IGNITION SYSTEM OPERATION • Carry out spark test. (See Spark Test) • Is strong blue spark visible at suspected cylinder? | Yes | Go to the next step.
No | Repair or replace malfunctioning part according to spark test result. Then go to Step 14.
9 | INSPECT FOR AIR SUCTION AT INTAKE-AIR SYSTEM • Inspect for air leakage at following: - Around connection of dynamic chamber and intake manifold - Around connection of intake manifold and cylinder head • Is air leakage found? | Yes | Repair or replace suspected part, then go to Step 14.
No | Go to the next step.
10 | INSPECT FUEL INJECTOR WIRING HARNESS • Remove intake air system parts. • Disconnect the fuel injector connector on suspected cylinder. • Connect the NOID LIGHT to fuel injector terminals. • Inspect dim of light during cranking. • Does the light illuminate? | Yes | Go to the next step.
No | Inspect the fuel injector wiring harnesses. Repair or replace it if necessary, then go to Step 14.
11 | INSPECT SEALING OF ENGINE COOLANT PASSAGE • Perform "ENGINE COOLANT LEAKAGE INSPECTION." (See ENGINE COOLANT LEAKAGE INSPECTION [L8, LF, L3, L3 Turbo].) • Is there any malfunction? | Yes | Repair or replace malfunctioning part according to inspection results. Then go to Step 14.
No | Go to the next step.
12 | INSPECT ENGINE COMPRESSION • Inspect the engine compression. (See COMPRESSION INSPECTION [L8, LF, L3].) • Is the engine compression normal? | Yes | Go to the next step.
No | Overhaul the engine, then go to the next step.
13 | INSPECT FUEL INJECTOR OPERATION • Remove the fuel injector from the suspected cylinder. • Switch the injector with the injector on other cylinder. • Start the engine and idle it. • Is the misfire DTC for cylinder which has a suspected fuel injector? | Yes | Replace the injector, then go to the next step.
No | Go to the next step.
14 | VERIFY TROUBLESHOOTING OF MISFIRE DTC COMPLETED • Make sure to reconnect all disconnected connectors. • Start the engine. • Clear the DTC from the PCM memory using the WDS or equivalent. • Perform the KOER self-test. (See KOEO/KOER SELF TEST [L8, LF, L3].) • Is the misfire DTC present? | Yes | Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION [L8, LF, L3].)
No | Go to the next step.
15 | VERIFY AFTER REPAIR PROCEDURE • Perform the "AFTER REPAIR PROCEDURE". (See AFTER REPAIR PROCEDURE [L8, LF, L3].) • Are any DTC present? | Yes | Go to the applicable DTC troubleshooting. (See DTC TABLE [L8, LF, L3].)
No | Troubleshooting completed.