DTC P0300: Random / Multiple Cylinder Misfire Detected; DTC P0301: Cylinder 1 Misfire Detected; DTC P0302: Cylinder 2 Misfire Detected; DTC P0303: Cylinder 3 Misfire Detected; DTC P0304: Cylinder 4 Misfire Detected: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
5. Read the DTCs.
   RESULT
   
   

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

   HINT: 

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

B → See step   37 

A: Go to next step 

1. Check the PCV hose connections. Refer to COMPONENTS .

   OK

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

NG → REPAIR OR REPLACE PCV HOSE 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / Gas Misfire / Misfire RPM and Misfire Load.
5. Read and note the Misfire RPM and Misfire Load values.

   HINT: 

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

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Clear the DTCs. Refer to DTC CHECK / CLEAR .
5. Put the engine in inspection mode (maintenance mode). Refer to INSPECTION MODE PROCEDURE .
6. Enter the following menus: Powertrain / Engine and ECT / Data List / Gas Misfire / Cylinder #1 (to #4) Misfire Count.
7. Allow the engine to idle.
8. Read each value for Cylinder #1 (to #4) Misfire Count displayed on the Techstream. If no misfire counts occur in any cylinders, perform steps [A] and [B], and then check the misfire counts again.
9. Drive the vehicle with the Misfire RPM and Misfire Load noted in the read value using the Techstream (Misfire RPM and Misfire Load) procedures above [A].
10. Read Cylinder #1 (to #4) Misfire Count or the DTCs displayed on the Techstream [B].
    RESULT
    
    

    Misfire Count	Proceed to
    Most misfires occur in only 1 or 2 cylinders	A
    3 cylinders or more have equal misfire counts	B

    HINT: 

    • If it is difficult to reproduce misfires for each cylinder, check the Data List item called Misfire Margin. Try to find vehicle driving conditions that lower the Misfire Margin value. Values above 30% are considered normal.
    • If the freeze frame data record of the engine coolant temperature is below 75°C (167°F), it may only be possible to detect the misfire when the engine is cold.

B → See step   18 

A: Go to next step 

1. Inspect the spark plug of the misfiring cylinder. Refer to ON-VEHICLE INSPECTION - Step 3 .

NG → See step   38 

OK: Go to next step 

1. Perform a spark test. Refer to ON-VEHICLE INSPECTION - Step 1 .

   HINT: 

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

NEXT: Go to next step 

1. Measure the cylinder compression pressure of the misfiring cylinder. Refer to ON-VEHICLE INSPECTION - Step 8 .

NG → CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION 

OK: Go to next step 

1. Disconnect the ECM connector.
   Fig 1: Checking Terminal Voltage (Power Source Of Fuel Injector Assembly)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Turn the power switch on (IG).
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   D27-85 (#10) - D27-109 (E01)	Power switch on (IG)	11 to 14 V
   D27-84 (#20) - D27-109 (E01)	Power switch on (IG)	11 to 14 V
   D27-83 (#30) - D27-109 (E01)	Power switch on (IG)	11 to 14 V
   D27-82 (#40) - D27-109 (E01)	Power switch on (IG)	11 to 14 V

   TEXT IN ILLUSTRATION
   
   

   *a	Front view of wire harness connector (to ECM)

NG → See step   45 

OK: Go to next step 

1. Check the fuel injector assembly injection (whether fuel volume is high or low, and whether injection pattern is poor). Refer to INSPECTION .

NG → See step   39 

OK: Go to next step 

1. Check the intake system for vacuum leaks. Refer to ON-VEHICLE INSPECTION .

   OK

   No leaks in intake system.

NG → REPAIR OR REPLACE INTAKE SYSTEM 

OK: Go to next step 

1. Check the fuel pressure. Refer to ON-VEHICLE INSPECTION - Step 2 .

NG → See step   36 

OK: Go to next step 

NG → See step   40 

OK: Go to next step 

NG → See step   31 

OK: Go to next step 

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Clear the DTCs. Refer to DTC CHECK / CLEAR .
5. Drive the vehicle accordance with the driving pattern described in Confirmation Driving Pattern.
6. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
7. Read the pending DTCs.
   RESULT
   
   

   Result	Proceed to
   DTC P0300, P0301, P0302, P0303 or P0304 is output	A
   DTC is not output	B

B → END 

A: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Put the engine in inspection mode (maintenance mode). Refer to INSPECTION MODE PROCEDURE .
5. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

   HINT: 

   The A/C switch and all accessory switches should be off.

6. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position / Data List / Primary / MAP.
7. Check the engine idling condition and MAP values in the Data List while performing the Active Test.

   HINT: 

   • Do not leave the EGR valve open for 10 seconds or more during the Active Test.
   • Be sure to return the EGR valve to step 0 when the Active Test is completed.
   • Do not open the EGR valve 30 steps or more during the Active Test.

   OK

   MAP and idling condition change in response to EGR step position.

   Standard

   -	EGR Step Position (Active Test)
   	0 Steps	0 to 30 Steps
   Idling condition	Steady idling	Idling changes from steady to rough idling or engine stalls
   MAP (Data List)	MAP value is 20 to 40 kPa (150 to 300 mmHg) (EGR valve is fully closed)	MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed

   HINT: 

   During Active Test, if the idling condition does not change in response to EGR step position, then there is probably a malfunction in the EGR valve.

   Result

   Result	Proceed to
   Outside of standard range	A
   Within standard range	B

B → See step   31 

A: Go to next step 

1. Remove the EGR valve assembly. Refer to REMOVAL .
2. Check if the EGR valve is stuck open.

   OK

   EGR valve is tightly closed.

   RESULT
   
   

   Result	Proceed to
   NG	A
   OK	B

B → See step   31 

A → See step   41 

1. Check the intake system for vacuum leaks. Refer to ON-VEHICLE INSPECTION .

   OK

   No leaks in intake system.

NG → REPAIR OR REPLACE INTAKE SYSTEM 

OK: Go to next step 

1. Check the fuel pressure. Refer to ON-VEHICLE INSPECTION - Step 2 .

NG → See step   36 

OK: Go to next step 

NG → See step   40 

OK: Go to next step 

NG → See step   31 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Put the engine in inspection mode (maintenance mode). Refer to INSPECTION MODE PROCEDURE .
5. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

   HINT: 

   The A/C switch and all accessory switches should be off.

6. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position / Data List / Primary / MAP.
7. Check the engine idling condition and MAP values in the Data List while performing the Active Test.

   HINT: 

   • Do not leave the EGR valve open for 10 seconds or more during the Active Test.
   • Be sure to return the EGR valve to step 0 when the Active Test is completed.
   • Do not open the EGR valve 30 steps or more during the Active Test.

   OK

   MAP and idling condition change in response to EGR step position.

   Standard

   -	EGR Step Position (Active Test)
   	0 Steps	0 to 30 Steps
   Idling condition	Steady idling	Idling changes from steady to rough idling or engine stalls
   MAP (Data List)	MAP value is 20 to 40 kPa (150 to 300 mmHg) (EGR valve is fully closed)	MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed

   HINT: 

   During Active Test, if the idling condition does not change in response to EGR step position, then there is probably a malfunction in the EGR valve.

   Result

   Result	Proceed to
   Outside of standard range	A
   Within standard range	B

B → See step   31 

A: Go to next step 

1. Remove the EGR valve assembly. Refer to REMOVAL .
2. Check if the EGR valve is stuck open.

   OK

   EGR valve is tightly closed.

NG → See step   41 

OK: Go to next step 

1. Remove the ignition coil assembly and the spark plug from the misfiring cylinder.
2. Inspect the spark plug of the misfiring cylinder. Refer to ON-VEHICLE INSPECTION - Step 3 .

NG → See step   38 

OK: Go to next step 

1. Perform a spark test. Refer to ON-VEHICLE INSPECTION - Step 1 .

   HINT: 

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

NEXT: Go to next step 

1. Measure the cylinder compression pressure of the misfiring cylinder. Refer to ON-VEHICLE INSPECTION - Step 8 .

NG → CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION 

OK: Go to next step 

1. Disconnect the ECM connector.
   Fig 2: Checking Terminal Voltage (Power Source Of Fuel Injector Assembly)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Turn the power switch on (IG).
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   D27-85 (#10) - D27-109 (E01)	Power switch on (IG)	11 to 14 V
   D27-84 (#20) - D27-109 (E01)	Power switch on (IG)	11 to 14 V
   D27-83 (#30) - D27-109 (E01)	Power switch on (IG)	11 to 14 V
   D27-82 (#40) - D27-109 (E01)	Power switch on (IG)	11 to 14 V

   TEXT IN ILLUSTRATION
   
   

   *a	Front view of wire harness connector (to ECM)

NG → See step   42 

OK: Go to next step 

1. Check the fuel injector assembly injection (whether fuel volume is high or low, and whether injection pattern is poor). Refer to INSPECTION .

NG → See step   39 

OK: Go to next step 

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Clear the DTCs. Refer to DTC CHECK / CLEAR .
5. Drive the vehicle accordance with the driving pattern described in Confirmation Driving Pattern.
6. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
7. Read the pending DTCs.
   RESULT
   
   

   Result	Proceed to
   DTC P0300, P0301, P0302, P0303 or P0304 is output	A
   DTC is not output	B

B → END 

A: Go to next step 

1. Check the connection and terminal contact pressure of connectors and wire harnesses between the mass air flow meter sub-assembly and ECM. Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE .

   HINT: 

   Repair any problems.

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Clear the DTCs. Refer to DTC CHECK / CLEAR .
5. Turn the power switch off and wait for 30 seconds.
6. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.
7. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
8. Input the DTC: P0300, P0301, P0302, P0303 or P0304.
9. Check the DTC judgment result.
   RESULT
   
   

   Result	Proceed to
   ABNORMAL (DTC P0300, P0301, P0302, P0303 or P0304 is output)	A
   NORMAL (DTC is not output)	B

B → END 

A: Go to next step 

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Replace the mass air flow meter sub-assembly. Refer to REMOVAL .

   HINT: 

   If the results of the inspections performed in steps 13 and 21 indicated no problem, proceed to the next step without replacing the mass air flow meter sub-assembly.

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Clear the DTCs. Refer to DTC CHECK / CLEAR .
5. Turn the power switch off and wait for 30 seconds.
6. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.
7. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
8. Input the DTC: P0300, P0301, P0302, P0303 or P0304.
9. Check the DTC judgment result.
   RESULT
   
   

   Result	Proceed to
   NORMAL (DTC is not output)	A
   ABNORMAL (DTC P0300, P0301, P0302, P0303 or P0304 is output)	B

B → See step   43 

A → END 

1. Check the fuel lines for leaks or blockage.

NG → REPAIR OR REPLACE FUEL LINE 

OK → See step   44