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 ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
5. Read the DTCs.

   HINT: 

   Write down indicated DTCs.

   Result

   Result	Proceed to
   DTC P0300, P0301, P0302, P0303 and/or P0304 is 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 P0304 are output, troubleshoot those DTCs first.

B → See step   29 

A: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / 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. Check the PCV hose connected.

   OK

   PCV hose is correctly connected and is not damaged.

NG → See step   30 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / Catalyst OT MF F/C.
5. Read the value displayed on the Techstream.

   Result

   Data List	Techstream Display	Proceed to
   Catalyst OT MF F/C	Avail	A
   	Not Avl	B

B → See step   6 

A: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine and ECT / Active Test / Prohibit the Catalyst OT Misfire prevent F/C.
5. Perform the Active Test.
   NOTE:

   When performing the Active Test, make sure the vehicle is stopped and either idling or being revved within 3000 rpm.

NEXT: Go to next step 

1. Enter the following menus: Powertrain / Engine and ECT / Data List / Misfire / Cylinder #1 Misfire Count, #2, #3 and #4.
2. Start the engine and allow the engine to idle.
3. Read each value for Cylinder #1 Misfire Count to #4 displayed on the Techstream. If no misfire counts occur in any cylinders, perform steps (d) and (e), and then check the misfire counts again.
4. Drive the vehicle with the Misfire RPM and Misfire Load noted in the "READ VALUE USING TECHSTREAM (MISFIRE RPM AND MISFIRE LOAD)" procedures above.
5. Read the Cylinder #1 Misfire Count to #4 or DTCs displayed on the Techstream.

   Result

   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.
   • If the freeze frame data record of the Engine Run Time is below 120 seconds, the misfire may be detected immediately after the engine is started.

B → See step   17 

A: Go to next step 

1. Remove the ignition coil assembly and the spark plug from the misfiring cylinder.
   Fig 1: Identifying Spark Plug Electrode Gap

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the spark plug electrode gap.

   Standard gap

   1.0 to 1.1 mm (0.0394 to 0.0433 in.)

3. Check the electrode for carbon deposits.
   RECOMMENDED SPARK PLUG
   
   

   Manufacturer	Product
   DENSO	SC20HR11

   NOTE:

   If the electrode gap is larger than standard, replace the spark plug. Do not adjust the electrode gap.

4. Reinstall the ignition coil assembly.

NG → See step   32 

OK: Go to next step 

1. Disconnect the injector connectors to prevent the engine from starting.
   Fig 2: Checking Spark And Ignition

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   WARNING:

   Always disconnect all injector connectors.

2. Remove the ignition coil assembly from the cylinder head.
3. Install the spark plug onto the ignition coil.
4. Touch the spark plug tip to the cylinder head.
5. Crank the engine for less than 2 seconds and check for sparks.
   NOTE:

   Do not crank the engine for more than 2 seconds.

   OK

   Sparks jump across electrode gap.

6. Install the ignition coil assembly.
7. Reconnect the injector connectors.

NG → See step   27 

OK: Go to next step 

1. Measure the cylinder compression pressure of the misfiring cylinder . Refer to ON-VEHICLE INSPECTION - Step 10 .

NG → CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION 

OK: Go to next step 

1. Disconnect the ECM connector.
   Fig 3: Identifying ECM Connector Terminals

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

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   B29-108 (#10) - B29-45 (E01)	Ignition switch ON	11 to 14 V
   B29-107 (#20) - B29-45 (E01)	Ignition switch ON	11 to 14 V
   B29-106 (#30) - B29-45 (E01)	Ignition switch ON	11 to 14 V
   B29-105 (#40) - B29-45 (E01)	Ignition switch ON	11 to 14 V

4. Reconnect the ECM connector.

NG → See step   33 

OK: Go to next step 

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

NG → See step   34 

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. Inspect the mass air flow meter . Refer to ON-VEHICLE INSPECTION .

NG → See step   36 

OK: Go to next step 

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

NG → See step   37 

OK: Go to next step 

NG → See step   38 

OK: Go to next step 

NG → See step   39 

OK → See step   40 

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. Inspect the mass air flow meter . Refer to ON-VEHICLE INSPECTION .

NG → See step   36 

OK: Go to next step 

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

NG → See step   37 

OK: Go to next step 

NG → See step   38 

OK: Go to next step 

1. Remove the ignition coil assembly and the spark plug of the misfiring cylinder.
   Fig 4: Identifying Spark Plug Electrode Gap

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the spark plug electrode gap.

   Standard gap

   1.0 to 1.1 mm (0.0394 to 0.0433 in.)

3. Check the electrode for carbon deposits.
   RECOMMENDED SPARK PLUG
   
   

   Manufacturer	Product
   DENSO	SC20HR11

   NOTE:

   If the electrode gap is larger than standard, replace the spark plug. Do not adjust the electrode gap.

4. Reinstall the ignition coil assembly.

NG → See step   35 

OK: Go to next step 

1. Disconnect the injector connectors to prevent the engine from starting.
   Fig 5: Checking Spark And Ignition

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   WARNING:

   Always disconnect all injector connectors.

2. Remove the ignition coil assembly from the cylinder head.
3. Install the spark plug onto the ignition coil assembly.
4. Touch the spark plug tip to the cylinder head.
5. Crank the engine for less than 2 seconds and check for spark.
   NOTE:

   Do not crank the engine for more than 2 seconds.

   OK

   Sparks jump across electrode gap.

6. Install the ignition coil assembly.
7. Reconnect the injector connectors.

NG → See step   27 

OK: Go to next step 

1. Measure the cylinder compression pressure of the misfiring cylinder . Refer to ON-VEHICLE INSPECTION - Step 10 .

NG → CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION 

OK: Go to next step 

1. Disconnect the ECM connector.
   Fig 6: Identifying ECM Connector Terminals

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

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   B29-108 (#10) - B29-45 (E01)	Ignition switch ON	11 to 14 V
   B29-107 (#20) - B29-45 (E01)	Ignition switch ON	11 to 14 V
   B29-106 (#30) - B29-45 (E01)	Ignition switch ON	11 to 14 V
   B29-105 (#40) - B29-45 (E01)	Ignition switch ON	11 to 14 V

4. Reconnect the ECM connector.

NG → See step   33 

OK: Go to next step 

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

NG → See step   34 

OK: Go to next step 

NG → See step   39 

OK → See step   40 

1. Change the installed spark plug to a known good spark plug.
   Fig 7: Checking Spark And Ignition

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Perform a spark test.
   WARNING:

   Always disconnect all injector connectors.

   NOTE:

   Do not crank the engine for more than 2 seconds.

   1. Install the spark plug into the ignition coil assembly and connect the ignition coil assembly connector.
   2. Disconnect the injector connectors.
   3. Ground the spark plug.
   4. Check if sparks occur while the engine is being cranked.

      OK

      Sparks jump across electrode gap.

NG → See step   28 

OK → See step   35 

1. Change the ignition coil assembly to a known good ignition coil.
   Fig 8: Checking Spark And Ignition

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Perform a spark test.
   WARNING:

   Always disconnect all injector connectors.

   NOTE:

   Do not crank the engine for more than 2 seconds.

   1. Install the spark plug into the ignition coil assembly and connect the ignition coil assembly connector.
   2. Disconnect the injector connector.
   3. Ground the spark plug.
   4. Check if sparks occur while the engine is being cranked.

      OK

      Sparks jump across electrode gap.

NG → See step   40 

OK → See step   31