ECD 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

If DTC P0301 is displayed, check the No. 1 cylinder.
If DTC P0302 is displayed, check the No. 2 cylinder.
If DTC P0303 is displayed, check the No. 3 cylinder.
If DTC P0304 is displayed, check the No. 4 cylinder.

For monitoring the misfire, the ECM uses the crankshaft position sensor and camshaft position sensor to monitor changes in the crankshaft rotation for each cylinder.
The ECM counts the number of times the engine speed fluctuation indicates that a misfire has occurred.
When the misfire rate equals or exceeds the threshold indicating that the engine condition has deteriorated, the ECM illuminates the MIL and sets a DTC.

Tech Tips

The cylinder, which has the compensation value for Injection Feedback Val #1, #2, #3 or #4 that varies from the other cylinders, may be malfunctioning.
If only DTCs P0300, P0301, P0302, P0303 and/or P0304 are present, an injector assembly mechanical malfunction or insufficient compression has probably occurred. An open or short in the ECM or injector circuit is unlikely.

P0300, P0301, P0302, P0303, P0304:
DTC Detection Drive Pattern	DTC Detection Condition	Trouble Area
Idling with warm engine for 10 minutes or more	Significant fluctuations in engine speed while idling (2 trip detection logic)	Injector assembly Open or short in engine wire harness Connector connection Compression pressure Valve clearance Valve timing ECM Low quality fuel Injector compensation code

Tech Tips

If DTC P0300, P0301, P0302, P0303 and/or P0304 is stored, the following symptoms may appear.

Rough idle
Engine stall
Lack of power

CAUTION / NOTICE / HINT

Note

When replacing the ECM and/or injector assembly, the ECM needs Registration and Initialization Click here.

Tech Tips

When the ECM must be replaced, before replacing the ECM, perform the "Learning Values Save" function using the intelligent tester. Then after installing the new ECM, perform all of the initialization/registrations for the "Learning Values Write" function by following the instructions shown on the tester display.
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, and other data from the time the malfunction occurred.

PROCEDURE

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0300, P0301, P0302, P0303, P0304)

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON and turn the tester on.
Enter the following menus: Powertrain / Engine and ECT / DTC.

Read the DTCs.

Result
Result	Proceed to
DTC P0300, P0301, P0302, P0303 and/or P0304	A
DTC P0300, P0301, P0302, P0303 and/or P0304 and other DTCs	B

Tech Tips

If any DTCs other than P0300, P0301, P0302, P0303 and/or P0304 are output, troubleshoot those DTCs first.

GO TO DTC CHART Click here

CHECK INJECTOR COMPENSATION CODE
1. Check the injector compensation codes Click here.
  
  OK
  
  The compensation codes stored in the ECM match the compensation codes of the installed injector assemblies.
NG
REGISTER INJECTOR COMPENSATION CODE Click here

OK
CHECK HARNESS AND CONNECTOR (IN ENGINE ROOM)
1. Check the wire harness and connector connections.
  
  OK
  
  The wire harnesses and connectors have been connected securely and there are good connections.
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR Click here

OK
READ VALUE USING INTELLIGENT TESTER (INJECTION FEEDBACK VAL #1 TO #4 AND INJECTION VOLUME)
1. Start the engine and drive the vehicle until the engine coolant temperature reaches 75°C (167°F) or more.
2. Allow the engine to idle for 30 seconds or more.
  
  Tech Tips
  
  The shift lever should be in neutral and the A/C switch and all accessory switches should be off.
3. Connect the intelligent tester to the DLC3.
4. Turn the tester on.
5. Enter the following menus: Powertrain / Engine and ECT / Data List / Injection Feedback Val. #1 to #4 and Injection Volume.
6. Read the value.
  
  Tech Tips
  
  When reading the values of Data List, confirm that PM regeneration is not activating (value of "After Injection Period" is 0) by entering the following menus: Powertrain / Engine and ECT / Data List / After Injection Period.
  
  If PM regeneration is activating (value of "After Injection Period" is not 0), drive the vehicle until the PM regeneration is complete (value of "After Injection Period" becomes 0).
  
  Standard
  
  The compensatory injection volume is between -4.9 mm³/st and 4.9 mm³/st
  Tech Tips
  - If the injection volume is malfunctioning, the compensatory injection volume is displayed -5.0 mm³/st or less or 5.0 mm³/st or more.
  - The compensatory injection volume is usually between -2.0 mm³/st and 2.0 mm³/st.
NEXT
PERFORM ACTIVE TEST USING INTELLIGENT TESTER (FUEL CUT FOR IDENTIFYING MALFUNCTIONING CYLINDER)
1. Connect the intelligent tester to the DLC3.
2. Start the engine and turn the tester on.
3. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Cylinder #1 to #4 Fuel Cut.
4. Check the 4 cylinders in sequence to identify a faulty cylinder by performing the Active Test / Control the Cylinder #1 to #4 Fuel Cut inspection.
  Tech Tips
  - DTCs may be output after this Active Test. Make sure to check for DTCs after this Active Test. If any DTCs are output, make sure to clear them Click here.
  - If the engine idle speed does not change when a fuel injection is disabled, the cylinder being tested is malfunctioning.
  - If the cylinder being tested is normal, there will be a significant change in idle speed when the fuel injection is stopped for that cylinder.
NEXT
CHECK CYLINDER COMPRESSION PRESSURE OF MALFUNCTIONING CYLINDER
1. Check the cylinder compression pressure Click here.
  
  OK
  
  The cylinder compression pressure is within the standard range.
NG
CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION Click here

OK
CHECK VALVE CLEARANCE OF MALFUNCTIONING CYLINDER
1. Check the valve clearance (See page ) and the valve timing Click here.
  
  OK
  
  The valve clearance and the valve timing are within the standard range.
NG
ADJUST VALVE CLEARANCE Click here

OK

OK
The compensation codes stored in the ECM match the compensation codes of the installed injector assemblies.

OK
The wire harnesses and connectors have been connected securely and there are good connections.

Standard
The compensatory injection volume is between -4.9 mm³/st and 4.9 mm³/st

OK
The cylinder compression pressure is within the standard range.

OK
The valve clearance and the valve timing are within the standard range.

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

Connect the intelligent tester to the DLC3.
Clear the DTCs Click here.
Turn the ignition switch off and wait for 30 seconds.
Start the engine and warm it up until the engine coolant temperature sensor reaches 75°C (167°F) or more.
Allow the engine to idle for more than 10 minutes.

Tech Tips

The shift lever should be in neutral, and the A/C switch and all accessory switches should be off.
Enter the following menus: Powertrain / Engine and ECT / DTC / Pending.

Read the pending DTCs.

Tech Tips

If no pending DTCs are output, proceed to the next step to check "All Readiness".
Perform the following procedure using the tester to determine whether or not the DTC judgment has been carried out.

Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input DTC P0300, P0301, P0302, P0303 and/or P0304.

Check the DTC judgment result.

Result
Tester Display	Result	Proceed to
Pending DTC	DTC P0300, P0301, P0302, P0303 and/or P0304	A
All Readiness	ABNORMAL	A
All Readiness	NORMAL	B

Tech Tips

If STATUS is INCOMPLETE or UNKNOWN, increase idling time.

CHECK FOR INTERMITTENT PROBLEMS Click here

REPLACE INJECTOR ASSEMBLY
1. Replace the injector assembly Click here.
NEXT
PERFORM REGISTRATION AND INITIALIZATION
1. Register the injector compensation code Click here.
2. Perform Pilot Quantity Learning Values Reset Click here.
NEXT
BLEED AIR FROM FUEL SYSTEM
1. Bleed air from fuel system Click here.
NEXT
CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED Click here
REGISTER INJECTOR COMPENSATION CODE
1. Register the injector compensation code Click here.
NEXT
CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED Click here
REPAIR OR REPLACE HARNESS OR CONNECTOR

NEXT
CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED Click here
ADJUST VALVE CLEARANCE
1. Adjust valve clearance Click here.
NEXT
CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED Click here
CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

NEXT
CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED
1. Connect the intelligent tester to the DLC3.
2. Clear the DTCs Click here.
3. Turn the ignition switch off and wait for 30 seconds.
4. Start the engine and warm it up until the engine coolant temperature sensor reaches 75°C (167°F) or more.
5. Allow the engine to idle for more than 10 minutes.
  
  Tech Tips
  
  The shift lever should be in neutral, and the A/C switch and all accessory switches should be off.
6. Enter the following menus: Powertrain / Engine and ECT / DTC / Pending.
7. Confirm that the Pending DTC is not output again.
  
  Tech Tips
  
  Perform the following procedure using the tester to determine whether or not the DTC judgment has been carried out.
  1. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
  2. Input DTC P0300, P0301, P0302, P0303 and/or P0304.
  3. Check that STATUS is NORMAL. If STATUS is INCOMPLETE or UNKNOWN, increase idling time.
NEXT
END