SFI SYSTEM, Diagnostic DTC:P0300, P0301, P0302, P0303

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

DESCRIPTION

When the engine misfires, high concentrations of hydrocarbons enter the exhaust gas. Extremely high hydrocarbon concentration levels can cause increases in exhaust emission levels. High concentrations of hydrocarbons can also cause increases in the three-way catalytic converter temperature, which may cause damage to the three-way catalytic converter. To prevent these increases in emissions and to limit the possibility of thermal damage, the ECM monitors the misfire rate. When the temperature of the three-way catalytic converter reaches the point of thermal degradation, the ECM blinks the MIL. To monitor misfires, the ECM uses the camshaft position sensor and the crankshaft position sensor. The camshaft position sensor is used to identify any misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. Misfires are counted as when the crankshaft rotation speed variations exceed predetermined thresholds.

If the misfire rate exceeds the threshold level, and could cause emission deterioration, the ECM illuminates the MIL and sets a DTC.

DTC No.	DTC Detection Condition	Trouble Area
P0300	Simultaneous misfiring of several cylinders detected (2-trip detection logic)	Open or short in engine wire harness Connector connection Vacuum hose connections Ignition system Fuel injector assembly Fuel pressure Manifold Absolute Pressure Sensor Engine coolant temperature sensor Compression pressure Valve clearance Valve timing PCV valve and hose PCV hose connection Air induction system EGR valve assembly ECM
P0301 P0302 P0303	Misfiring of specific cylinder detected (2-trip detection logic)

DTC No.

DTC Detection Condition

Trouble Area

P0300

Simultaneous misfiring of several cylinders detected

(2-trip detection logic)

Open or short in engine wire harness
Connector connection
Vacuum hose connections
Ignition system
Fuel injector assembly
Fuel pressure
Manifold Absolute Pressure Sensor
Engine coolant temperature sensor
Compression pressure
Valve clearance
Valve timing
PCV valve and hose
PCV hose connection
Air induction system
EGR valve assembly
ECM

P0301

P0302

P0303

Misfiring of specific cylinder detected

(2-trip detection logic)

When DTCs for misfiring cylinders are randomly set, but DTC P0300 is not set, it indicates that misfires have been detected in different cylinders at different times. DTC P0300 is only set when several misfiring cylinders are detected at the same time.

WIRING DIAGRAM

CONFIRMATION DRIVING PATTERN

Connect an intelligent tester to the DLC3.
Turn the ignition switch to ON.
Turn the tester on.
Record DTCs and freeze frame data.
Using the tester, switch the ECM from normal mode to check mode Click here.
Read the misfire counts of each cylinder (Cylinder #1, #2, and #3) with the engine in an idling condition. If any misfire count is displayed, skip the following confirmation driving pattern.

Drive the vehicle several times with the conditions, such as engine rpm and engine load, shown in Misfire RPM and Misfire Load in the Data List.

Tech Tips

In order to store misfire DTCs, it is necessary to drive the vehicle for the period of time shown in the table below, with the Misfire RPM and Misfire Load in the Data List.

Engine RPM	Duration
Idling	8 minutes or more
1000	4 minutes 30 seconds or more
2000	2 minute 30 seconds or more
3000	1 minute 30 seconds or more

Check whether misfires have occurred by checking for DTCs and freeze frame data.

Tech Tips

Do not turn the ignition switch off until the stored DTC(s) and freeze frame data have been recorded. When the ECM returns to normal mode (default), the stored DTC(s), freeze frame data and other data will be cleared.
Record the DTC(s), freeze frame data and misfire counts.
Turn the ignition switch off and wait for at least 5 seconds.

INSPECTION PROCEDURE

Note

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

Tech Tips

If any DTCs other than misfire DTCs are output, troubleshoot those DTCs first.
Read freeze frame data using an intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.
If the misfire does not recur when the vehicle is brought to the workshop, reproduce the conditions stored in the freeze frame data.
If the misfire still cannot be reproduced even though the conditions stored in the freeze frame data have been duplicated, one of the following factors is considered to be a possible cause of the problem:

The fuel level is low.
Improper fuel is used.
The spark plugs are dirty.
The problem is complex and involves multiple factors.

After finishing repairs, check that no misfire occurs in each cylinder (Cylinder #1, #2, and #3).
Be sure to confirm that no misfiring cylinder DTCs are set again by conducting the confirmation driving pattern, after the repairs.
When either Short FT #1 or Long FT #1 in the freeze frame data is outside the range of +/-20%, the air fuel ratio may be rich (-20% or less) or lean (+20% or more).
When the Coolant Temp in the freeze frame data is less than 75°C (167°F), the misfires occurred only while warming up the engine.
An extremely imbalanced drive wheel which causes body vibration may cause misfire DTCs detection.

PROCEDURE

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

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

Read the DTC.

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

GO TO DTC CHART Click here

PERFORM ACTIVE TEST USING INTELLIGENT TESTER (OPERATE EGR VALVE)

Connect the intelligent tester to the DLC3.
Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

Tech Tips

The A/C switch and all accessory switches should be off.
Turn the intelligent tester on.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position.

Check the MAP in Data List and the idling condition while performing 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

30 to 40 Steps or Higher

Idling condition

Steady idling

Engine changes from steady to rough idling

Engine changes from rough idling to engine stall

MAP value

(Data List)

28 to 48 kPa

(EGR valve is fully closed)

MAP value is at least +10 to 15 kPa higher than when EGR valve is fully closed

80 to 110 kPa

(After engine stall)

Tech Tips

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

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

READ VALUE USING INTELLIGENT TESTER (MISFIRE RPM AND MISFIRE LOAD) Click here

CHECK WHETHER DTC OUTPUT RECURS

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON.
Turn the tester on.
Clear the DTC.
Turn the ignition switch off and wait for 30 seconds.
Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

Tech Tips

The A/C switch and all accessory switches should be off.
Switch the ECM from normal mode to check mode.
Drive the vehicle at 60 km/h (37 mph) with the shift lever in B.
CAUTION:
- Strictly observe speed limits and traffic laws when performing the confirmation drive pattern.
Perform fuel-cut operation for 5 seconds or more, with the accelerator pedal fully released.
Tech Tips
- If the deceleration was not completed, perform the confirmation driving pattern again.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTCs to be confirmed.

Check the DTC judgment result.

Result
Result	Proceed to
No output	A
P0401	B

Intelligent Tester
Tester Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment not completed You should perform driving pattern after confirming DTC enabling conditions
UNKNOWN	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU's memory limit

Tech Tips

If the DTC judgment result is INCOMPLETE or UNKNOWN, drive the vehicle again at 60 km/h (37 mph) with the shift lever in B, perform fuel-cut operation for 5 seconds or more with the accelerator pedal fully released, and check the DTC judgment result.

GO TO DTC CHART Click here

READ VALUE USING INTELLIGENT TESTER (MISFIRE RPM AND MISFIRE LOAD)
1. Connect the intelligent tester to the DLC3.
2. Turn the ignition switch to ON and turn the tester on.
3. Enter the following menus: Powertrain / Engine / Data List / Misfire RPM and Misfire Load.
4. Read and note the Misfire RPM and Misfire Load values.
  
  Tech Tips
  
  The Misfire RPM and Misfire Load values indicate the vehicle conditions under which the misfire occurred.
NEXT
CHECK PCV HOSE (HOSE CONNECTIONS)
1. Check the PCV hose connections Click here.
  
  OK
  
  PCV hose is connected correctly and is not damaged.
NG
REPAIR OR REPLACE PCV HOSE

OK

OK
PCV hose is connected correctly and is not damaged.

READ VALUE USING INTELLIGENT TESTER

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON.
Turn the tester on (Step "A").
Enter the following menus: Powertrain / Engine / Data List / Cylinder #1 (to #3) Misfire Count (Step "B").
Read each value for Cylinder #1 (to #3) Misfire Count displayed on the tester. If no misfire counts occur in any cylinders, perform the following procedure:
1. Start the engine and let it idle.
2. Move the shift lever to D.
3. Check the Cylinder #1 (to #3) Misfire Count.
4. If misfire counts are still not displayed, perform steps ("A") and ("B").
Drive the vehicle while satisfying the Misfire RPM and Misfire Load values noted in the "Read Value Using Intelligent Tester (Misfire RPM and Misfire Load)" procedure above.

Read Cylinder #1 (to #3) Misfire Count or the DTCs displayed on the tester.

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

Tech Tips

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 Coolant Temp value of the freeze frame data is below 75°C (167°F), the misfire may be detected only when the engine is cold.
Engine Run Time value of the freeze frame data is below 120 seconds, the misfire may be detected immediately after the engine is started.

CHECK AIR INDUCTION SYSTEM Click here

INSPECT SPARK PLUG

Remove the ignition coil and the spark plug of the misfiring cylinder.
Measure the spark plug electrode gap.

Maximum gap

1.1 mm (0.043 in.)

Maximum gap
1.1 mm (0.043 in.)

Check the electrode for carbon deposits.

Recommended Spark Plug
Manufacturer	Product
DENSO	SK16HR11

Note

If the electrode gap is out of range, replace the spark plug. Do not adjust the electrode gap.

Reinstall the ignition coil and the spark plug.

REPLACE SPARK PLUG Click here

CHECK FOR SPARKS AND IGNITION
1. Perform a spark test.
  
  CAUTION:
  
  During the test, disconnect all of the fuel injector assembly connectors.
  
  Note
  
  Do not crank the engine for more than 2 seconds.
  1. Remove the ignition coil from the cylinder head.
  2. Install the spark plug onto the ignition coil.
  3. Disconnect the all of the fuel injector assembly connectors.
  4. Touch the spark plug to the cylinder head.
  5. Crank the engine for less than 2 seconds and check for spark.
    
    OK
    
    Sparks jump across electrode gap.
  6. Reconnect the all of the fuel injector assembly connectors.
  7. Reinstall the ignition coil.
NG
CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER Click here

OK
CHECK CYLINDER COMPRESSION PRESSURE
1. Measure the cylinder compression pressure of the misfiring cylinder Click here.
NG
CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

OK

OK
Sparks jump across electrode gap.

CHECK HARNESS AND CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)

Text in Illustration
*1	Front view of wire harness connector: (to Fuel Injector Assembly)
*2	Front view of wire harness connector: (to ECM)

Disconnect the fuel injector assembly connectors.
Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
C1-2 - B8-86 (#10)	Always	Below 1 Ω
C2-2 - B8-85 (#20)	Always	Below 1 Ω
C3-2 - B8-84 (#30)	Always	Below 1 Ω

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
C1-2 or B8-86 (#10) - Body ground	Always	10 kΩ or higher
C2-2 or B8-85 (#20) - Body ground	Always	10 kΩ or higher
C3-2 or B8-84 (#30) - Body ground	Always	10 kΩ or higher

Reconnect the fuel injector assembly connectors.
Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

INSPECT ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, AND/OR #30 VOLTAGE)

Text in Illustration

*1
Front view of wire harness connector:

(to ECM)

Disconnect the ECM connector.
Turn the ignition switch to ON.

Text in Illustration
*1	Front view of wire harness connector: (to ECM)

Measure the voltage according to the value(s) in the table below.

Standard Voltage

Tester Connection	Switch Condition	Specified Condition
B8-86 (#10) - B8-46 (E01)	Ignition switch ON	11 to 14 V
B8-85 (#20) - B8-46 (E01)	Ignition switch ON	11 to 14 V
B8-84 (#30) - B8-46 (E01)	Ignition switch ON	11 to 14 V

Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - ECM)

CHECK FUEL INJECTOR ASSEMBLY OF MISFIRING CYLINDER
1. Check the fuel injector assembly injection (whether fuel volume is high or low, and whether injection pattern is poor) Click here.
NG
REPLACE FUEL INJECTOR ASSEMBLY Click here

OK
CHECK VALVE CLEARANCE OF MISFIRING CYLINDER
1. Check the valve clearance of misfiring cylinder Click here.
NG
ADJUST VALVE CLEARANCE Click here

OK
CHECK AIR INDUCTION SYSTEM
1. Check the intake system for vacuum leaks Click here.
  
  OK
  
  No leaks in intake system.
NG
REPAIR OR REPLACE AIR INDUCTION SYSTEM

OK
CHECK VALVE TIMING

Tech Tips

Check the valve timing Click here.

NG
ADJUST VALVE TIMING Click here

OK
CHECK FUEL PRESSURE
1. Check the fuel pressure Click here.
NG
CHECK AND REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE AND FILTER

OK
READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)
1. Connect an intelligent tester to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the tester on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.
5. Read the value.
  
  Standard
  
  Between 80°C and 100°C (176°F and 212°F) with warm engine.
NG
REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here

OK
INSPECT MANIFOLD ABSOLUTE PRESSURE SENSOR

Tech Tips

Inspect the manifold absolute pressure sensor Click here.

NG
REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR Click here

OK

REPLACE ECM Click here
CHECK AIR INDUCTION SYSTEM
1. Check the intake system for vacuum leaks Click here.
  
  OK
  
  No leaks in intake system.
NG
REPAIR OR REPLACE AIR INDUCTION SYSTEM

OK
CHECK VALVE TIMING

Tech Tips

Check the valve timing Click here.

NG
ADJUST VALVE TIMING Click here

OK
CHECK FUEL PRESSURE
1. Check the fuel pressure Click here.
NG
CHECK AND REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE AND FILTER

OK
READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)
1. Connect an intelligent tester to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the tester on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.
5. Read the value.
  
  Standard
  
  Between 80°C and 100°C (176°F and 212°F) with warm engine.
NG
REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here

OK
INSPECT MANIFOLD ABSOLUTE PRESSURE SENSOR

Tech Tips

Inspect the manifold absolute pressure sensor Click here.

NG
REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR Click here

OK

OK
No leaks in intake system.

INSPECT SPARK PLUG

Remove the ignition coil and the spark plug of the misfiring cylinder.
Measure the spark plug electrode gap.

Maximum gap

1.1 mm (0.043 in.)

Check the electrode for carbon deposits.

Recommended Spark Plug
Manufacturer	Product
DENSO	SK16HR11

Note

If the electrode gap is out of range, replace the spark plug. Do not adjust the electrode gap.

Reinstall the ignition coil and the spark plug.

REPLACE SPARK PLUG Click here

CHECK FOR SPARK AND IGNITION
1. Perform a spark test.
  
  CAUTION:
  
  During the test, disconnect all of the fuel injector assembly connectors.
  
  Note
  
  Do not crank the engine for more than 2 seconds.
  1. Remove the ignition coil from the cylinder head.
  2. Install the spark plug onto the ignition coil.
  3. Disconnect the all of the fuel injector assembly connectors.
  4. Touch the spark plug to the cylinder head.
  5. Crank the engine for less than 2 seconds and check for spark.
    
    OK
    
    Sparks jump across electrode gap.
  6. Reconnect the all of the fuel injector assembly connectors.
  7. Reinstall the ignition coil.
NG
CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER Click here

OK
CHECK CYLINDER COMPRESSION PRESSURE OF MISFIRING CYLINDER
1. Measure the cylinder compression pressure of the misfiring cylinder Click here.
NG
CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

OK

CHECK HARNESS AND CONNECTOR (FUEL INJECTOR ASSEMBLY - ECM)

Text in Illustration
*1	Front view of wire harness connector: (to Fuel Injector)
*2	Front view of wire harness connector: (to ECM)

Disconnect the fuel injector assembly connectors.

Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
C1-2 - B8-86 (#10)	Always	Below 1 Ω
C2-2 - B8-85 (#20)	Always	Below 1 Ω
C3-2 - B8-84 (#30)	Always	Below 1 Ω

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
C1-2 or B8-86 (#10) - Body ground	Always	10 kΩ or higher
C2-2 or B8-85 (#20) - Body ground	Always	10 kΩ or higher
C3-2 or B8-84 (#30) - Body ground	Always	10 kΩ or higher

Reconnect the fuel injector assembly connectors.
Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

INSPECT ECM TERMINAL OF MISFIRING CYLINDER (#10, #20, AND/OR #30 VOLTAGE)

Text in Illustration

*1
Front view of wire harness connector:

(to ECM)

Disconnect the ECM connector.
Turn the ignition switch to ON.

Measure the voltage according to the value(s) in the table below.

Standard Voltage

Tester Connection	Switch Condition	Specified Condition
B8-86 (#10) - B8-46 (E01)	Ignition switch ON	11 to 14 V
B8-85 (#20) - B8-46 (E01)	Ignition switch ON	11 to 14 V
B8-84 (#30) - B8-46 (E01)	Ignition switch ON	11 to 14 V

Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - ECM)

CHECK FUEL INJECTOR ASSEMBLY OF MISFIRING CYLINDER
1. Check the fuel injector assembly injection (whether fuel volume is high or low, and whether injection pattern is poor) Click here.
NG
REPLACE FUEL INJECTOR ASSEMBLY Click here

OK
CHECK VALVE CLEARANCE OF MISFIRING CYLINDER
1. Check the valve clearance of misfiring cylinder Click here.
NG
ADJUST VALVE CLEARANCE Click here

OK

REPLACE ECM Click here
CHANGE TO NORMAL SPARK PLUG AND CHECK SPARK OF MISFIRING CYLINDER
1. Change the installed spark plug to a known good spark plug.
2. Perform a spark test.
  
  CAUTION:
  
  During the test, disconnect all of the fuel injector assembly connectors.
  
  Note
  
  Do not crank the engine for more than 2 seconds.
  1. Remove the ignition coil from the cylinder head.
  2. Install the spark plug onto the ignition coil.
  3. Disconnect the all of the fuel injector assembly connectors.
  4. Touch the spark plug to the cylinder head.
  5. Crank the engine for less than 2 seconds and check for spark.
    
    OK
    
    Sparks jump across electrode gap.
  6. Reconnect the all of the fuel injector assembly connectors.
  7. Reinstall the ignition coil.
NG
CHANGE TO NORMAL IGNITION COIL AND CHECK SPARK OF MISFIRING CYLINDER Click here

OK

REPLACE SPARK PLUG Click here
CHANGE TO NORMAL IGNITION COIL AND CHECK SPARK OF MISFIRING CYLINDER
1. Change the installed ignition coil to a known good ignition coil.
2. Perform a spark test.
  
  CAUTION:
  
  During the test, disconnect all of the fuel injector assembly connectors.
  
  Note
  
  Do not crank the engine for more than 2 seconds.
  1. Remove the ignition coil from the cylinder head.
  2. Install the spark plug onto the ignition coil.
  3. Disconnect the all of the fuel injector assembly connectors.
  4. Touch the spark plug to the cylinder head.
  5. Crank the engine for less than 2 seconds and check for spark.
    
    OK
    
    Sparks jump across electrode gap.
  6. Reconnect the all of the fuel injector assembly connectors.
  7. Reinstall the ignition coil.
NG
REPLACE ECM Click here

OK

REPLACE IGNITION COIL Click here