DTC P0300 [AJ (3.0L Duratec)]

DTC P0300	Random misfire
DETECTION CONDITION	• The PCM detects that multiple cylinders are misfiring or the PCM cannot identify which cylinder is misfiring.
POSSIBLE CAUSE	• Damaged camshaft position sensor • Low fuel level: less than 1/8 tank • EGR valve stuck open

STEP

INSPECTION

ACTION

1
VERIFY FREEZE FRAME DATA HAS BEEN RECORDED
• Has FREEZE FRAME DATA been recorded?

Yes

Go to the next step.

No

Record the FREEZE FRAME DATA on the repair order, then go to next step.

2
VERIFY REPAIR INFORMATION AVAILABILITY
• Verify related service repair information availability.

• Is any related repair information available?

Yes

Perform repair or diagnosis according to the available repair information.

• If the vehicle is not repaired, go to the next step.

No

Go to the next step.

3
CHECK FOR ADAPTIVE FUEL MONITOR AND HO2S CONTINUOUS MEMORY DTCS

Note

• Following is a list of non-misfire DTCs to look for in the Continuous Memory.

• Retrieve the continuous memory DTC from PCM.

• Are any of DTCs P0136, P0156, P0171, P0172, P0174, P0175, P1130 and/or P1150 displayed?

Yes

Go to Step 5.

No

Go to the next step.

4
CHECK FOR OTHER NON-MISFIRE CONTINUOUS MEMORY DTCS

Note

• Following is a list of non-misfire DTCs to look for in the Continuous Memory.

• Are other non-misfire DTCs present?

Yes

Go to applicable DTC inspection.

(See DTC TABLE [AJ (3.0L Duratec)].)

No

Go to the next step.

5
CKECK FOR KEY ON ENGINE OFF (KOEO) SELF TEST
• Perform the KOEO self test.

• Are any KOEO DTCs displayed?

Yes

Go to applicable DTC inspection.

(See DTC TABLE [AJ (3.0L Duratec)].)

No

Inspect spark plugs and ignition coil.

If okay, go to the next step.

6
CHECK FOR OTHER KEY ON ENGINE RUNNING (KOER) SELF EST

Note

• Check any KOER DTCs, which can cause the Misfire DTC.

• Perform the KOER self test.

• Are any additional KOER DTCs displayed?

Yes

If the DTCs P1132, P1138, P1152, P1158, P1131, P1137, P1151 or P1157 are present:

Go to Step 9.

All others:

Go to applicable DTC inspection.

(See DTC TABLE [AJ (3.0L Duratec)].)

No

Go to the next step.

7
CHECK/COMPARE PID VALUES
• Start the engine and warm up to normal operating temperature.

• Access DPFEGR PID.

• Record DPFEGR PID value.

• Turn the ignition switch to OFF.

• Turn the ignition switch to ON.

• Access DPFEGR PID.

• Compare ignition switch ON position (engine off) and idle PID values.

• Was the idle PID value within 0.15 V of ignition switch ON position (engine off) value?

Yes

Go to the next step.

No

Go to Step 25.

8
EGR RESTRICTION/FLOW TEST

Note

• Check any KOER DTCs, which can cause the Misfire DTC.

• Record and clear DTCs.

• Disconnect the vacuum line at EGR valve and plug the vacuum line.

• Complete Misfire Monitor Drive Mode.

• Is P0300 still present?

Yes

Go to the next step.

No

Inspect for the intake manifold and the EGR valve, then go to Step 26.

9
CHECK INJECTOR DRIVER PIDS INJ1F THROUGH INJ6F
• Turn the ignition switch ON.

• Access INJ1F, INJ2F, INJ3F, INJ4F, INJ5F and INJ6F PIDs.

• Are the PIDs status Yes?

Yes

Go to the next step.

No

Go to Step 11.

10
CHECK FUEL INJECTORS AND HARNESSES FOR OPEN
• Disconnect PCM.

• Measure resistance following at PCM harness side connector.

- Between terminal 75 (R.H.D.) /E-2 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (for fuel injector No.1)

- Between terminal 101 (R.H.D.) /E-5 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (for fuel injector No.2)

- Between terminal 74 (R.H.D.) /E-13 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (for fuel injector No.3)

- Between terminal 100 (R.H.D.) /E-4 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (for fuel injector No.4)

- Between terminal 73 (R.H.D.) /E-3 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (for fuel injector No.5)

- Between terminal 99 (R.H.D.) /E-15 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (for fuel injector No.6)

• Is the resistance 10-18 ohms?

Yes

Replace the PCM, then go to Step 26.

No

Go to Step 21.

11
CHECK FUEL PRESSURE
• Install fuel pressure gauge.

• Start and run the engine at idle.

• Record fuel pressure.

• Increase engine speed to 2,500 rpm and maintain for 1 min.

• Note and compare fuel pressure.

• Is the fuel pressure at the specified pressure?

(See FUEL LINE PRESSURE INSPECTION [AJ (3.0L Duratec)].)

Yes

Go to the next step.

No

Repair or replace malfunctioning part, then go to Step 26.

12
CHECK ABILITY OF FUEL SYSTEM TO HOLD FUEL PRESSURE
• Start and run engine at idle. Note the pressure.

• Increase engine speed to 2,500 rpm and maintain for 1 min.

• Look for fuel leakage at the fuel injector O-ring, fuel pressure regulator, and the fuel lines to the fuel charging assembly.

• Did fuel pressure remain at specification within 34 kPa {5 psi} for 1 min.

Yes

Go to the next step.

No

Repair or replace malfunctioning part, then go to Step 26.

13
CHECK FUEL INJECTOR FOR FLOW AND LEAKAGE
• Measure the flow rate for each fuel injector

(See FUEL INJECTOR INSPECTION [AJ (3.0L Duratec)].)

• Is flow rate for each fuel injector within specification?

Yes

Fuel delivery system is not likely to have caused the Misfire DTC.

Go to the next step.

No

Replace or clean inoperative fuel injector, then go to Step 26.

14
CHECK VACUUM SYSTEM

Note

• Some vacuum leaks can be heard.

• Inspect for all vacuum lines for damage, such as pinched lines, cracks, proper routing and assembly.

• Is the vehicle vacuum system okay?

Yes

Go to the next step.

No

Repair or replace malfunctioning part, then go to Step 26.

15
CHECK DAMPER AND PULLEY ASSEMBLY

Note

• This pinpoint step is for engines that have damper mounted pulse rings. Remove the front cover if necessary to observe the crankshaft pulley.

• Observe the crankshaft pulley for wobble.

• Examine the EI pulse ring fastened to the harmonic fastener.

• Does the crank pulley wobble or is pulse ring loose or damaged?

Yes

Replace the pulley or damper assembly, disconnect battery for 5 min to allow PCM to learn mew data.

Then go to Step 26.

No

Go to the next step.

16
CHECK EVAPORATIVE EMISSION SYSTEM

Note

• The misfire monitor can be influenced by evaporative emission system. The next five pinpoint test steps will diagnose the evaporative emission system.

• Check the charcoal canister for fuel saturation.

• Is there an excess amount of liquid fuel present in the fuel vapor storage charcoal canister?

Yes

Repair or replace malfunctioning part, then go to Step 26.

No

Go to the next step.

17
CHECK VACUUM IN EVAPORATIVE EMISSION SYSTEM SOLENOID VALVE
• Check for blockage/restrictions or cut hose between engine vacuum port and charcoal canister.

• Check for blockage in fuel tank vent system.

• Is there a fault indicated?

Yes

Repair or replace malfunctioning part, then go to Step 26.

No

Go to the next step.

18
CHECK OF PURGE SOLENOID VALVE HOUSING LEAKS
• Purge solenoid valve electrically connected.

• Install a hand vacuum pump to the vapor port from charcoal canister on the purge solenoid valve vacuum at line.

• Apply 53 kPa {16 in Hg} of vacuum with the vacuum pump.

• Does the purge solenoid valve hold vacuum at room temperature?

Yes

Go to the next step.

No

Replace purge solenoid valve, then go to Step 26.

19
CHECK FOR FILTER CONTAMINATION ON DAMAGE PURGE SOLENOID VALVE
• Vacuum line from input vacuum port to intake manifold on the purge solenoid valve (control vacuum solenoid part of valve) removed.

• Install a hand held vacuum pump to the open input vacuum port on the purge solenoid valve.

• Apply 48-52kPa {10-15 inHg} of vacuum to the purge solenoid valve.

• Does the purge solenoid valve hold vacuum, or is the valve very slow to release vacuum to atmosphere?

Yes

Replace purge solenoid valve filter.

If unable to clean filter or remove blockage to filter, replace purge solenoid valve.

Then go to Step 26.

No

Go to the next step.

20
CHECK FOR BASE ENGINE CONCERNS

Note

• This pinpoint test step will determine if there are any base engine concerns the may have caused the misfire DTC or drive concern.

• Engine temperature may affect results.

• Perform the following tests in order to evaluate base engine integrity:

- Compression and leak down test

- Valve train analysis

- PCV system

- Possible leakage points

• Is any service required?

Yes

Overhaul the engine.

(See ENGINE WORKSHOP MANUAL.)

Then go to Step 26.

No

Intermittent concern exist, then go to Step 26.

21
CHECK FUEL INJECTOR HARNESS RESISTANCE
• Disconnect the malfunctioning fuel injector in Step 10.

• Measure the resistance for following at harness side connector:

- Between fuel injector No.1 terminal 2 and PCM terminal 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ1F, P0201)

- Between fuel injector No.1 terminal 1 and PCM terminal 75 (R.H.D.) /E-2 (L.H.D.) (INJ1F, P0201)

- Between fuel injector No.2 terminal 2 and PCM terminal 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ2F, P0202)

- Between fuel injector No.2 terminal 1 and PCM terminal 101 (R.H.D.) /E-5 (L.H.D.) (INJ2F, P0202)

- Between fuel injector No.3 terminal 2 and PCM terminal 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ3F, P0203)

- Between fuel injector No.3 terminal 1 and PCM terminal 74 (R.H.D.) /E-13 (L.H.D.) (INJ3F, P0203)

- Between fuel injector No.4 terminal 2 and PCM terminal 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ4F, P0204)

- Between fuel injector No.4 terminal 1 and PCM terminal 100 (R.H.D.) /E-4 (L.H.D.) (INJ4F, P0204)

- Between fuel injector No.5 terminal 2 and PCM terminal 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ5F, P0205)

- Between fuel injector No.5 terminal 1 and PCM terminal 73 (R.H.D.) /E-3 (L.H.D.) (INJ5F, P0205)

- Between fuel injector No.6 terminal 2 and PCM terminal 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ6F, P0206)

- Between fuel injector No.6 terminal 1 and PCM terminal 99 (R.H.D.) /E-15 (L.H.D.) (INJ6F, P0206)

• Is each resistance less than 5.0 ohms?

Yes

Go to the next step.

No

Repair for open circuit, then go to Step 26.

22
CHECK FUEL INJECTOR HARNESS CIRCUIT FOR SHORT TO POWER AND GROUND
• Disconnect PCM.

• Malfunctioning fuel injector in Step 10 disconnected.

• Measure resistance for following at PCM harness side connector.

- Terminal 75 (R.H.D.) /E-2 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ1F, P0201)

- Terminal 75 (R.H.D.) /E-2 (L.H.D.) and 24, 51, 76, 103 (R.H.D.) /C-48, C-49 (L.H.D.) (INJ1F, P0201)

- Terminal 101 (R.H.D.) /E-5 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ2F, P0202)

- Terminal 101 (R.H.D.) /E-5 (L.H.D.) and 24, 51, 76, 103 (R.H.D.) /C-48, C-49 (L.H.D.) (INJ2F, P0202)

- Terminal 74 (R.H.D.) /E-13 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ3F, P0203)

- Terminal 74 (R.H.D.) /E-13 (L.H.D.) and 24, 51, 76, 103 (R.H.D.) /C-48, C-49 (L.H.D.) (INJ3F, P0203)

- Terminal 100 (R.H.D.) /E-4 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ4F, P0204)

- Terminal 100 (R.H.D.) /E-4 (L.H.D.) and 24, 51, 76, 103 (R.H.D.) /C-48, C-49 (L.H.D.) (INJ4F, P0204)

- Terminal 73 (R.H.D.) /E-3 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ5F, P0205)

- Terminal 73 (R.H.D.) /E-3 (L.H.D.) and 24, 51, 76, 103 (R.H.D.) /C-48, C-49 (L.H.D.) (INJ5F, P0205)

- Terminal 99 (R.H.D.) /E-15 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ6F, P0206)

- Terminal 99 (R.H.D.) /E-15 (L.H.D.) and 24, 51, 76, 103 (R.H.D.) /C-48, C-49 (L.H.D.) (INJ6F, P0206)

• Is each resistance greater than10,000 ohms?

Yes

Go to the next step.

No

Repair for short circuit, then go to Step 26.

23
INSPECT FUEL INJECTOR(S)
• Inspect fuel injectors.

(See FUEL INJECTOR INSPECTION [AJ (3.0L Duratec)].)

• Are fuel injectors okay?

Yes

Go to the next step.

No

Replace suspected fuel injector, then go to Step 26.

24
INSPECT INDUCTION SYSTEM FOR AIR LEAKS
• Inspect the following areas for signs of air leaks:

- Inlet tube(s) from air cleaner to throttle body

- Gaskets which seal the upper and lower intake manifold.

- Vacuum hoses and lines for cranks and proper connections.

- PCV system.

• Are there any signs of leaks or damage?

Yes

Repair or replace malfunctioning part, then go to Step 26.

No

Intermittent malfunction exist, go to the Step 26.

25
CHECK FOR EGR FLOW WITH EGR VACUUM HOSE DISCONNECTED AND PLUGGED
• Disconnect vacuum hose at EGR valve and plug hose.

• Connect the WDS or equivalent to DLC.

• Turn then ignition switch to ON.

• Access DPFEGR PID and note PID value.

• Start the engine and bring idle.

• With engine at idle, look at the DPFEGR PID value and compare to the engine off reading. An increase in the PID value at idle indicates that the D.P.F.EGR sensor is sensing EGR flow.

• Is the DPFEGR PID value greater at idle by a minimum of 0.15 V than with the engine off?

Yes

Remove and inspect the EGR valve for signs of contamination, unusual wear, carbon deposits, binding and other damage.

Repair or replace the EGR valve, according to inspection result.

Then go to the next step.

No

Inspect the EGR solenoid valve and solenoid valve filter for restrictions.

Repair or replace malfunctioning part, then go to the next step.

26
VERIFY TROUBLESHOOTING OF DTC P0300 COMPLETED
• Make sure to reconnect all disconnected connectors.

• Clear the DTC from the PCM memory using the WDS or equivalent.

• Perform KOER self test.

(See KOEO/KOER SELF-TEST [AJ (3.0L Duratec)].)

• Is the PENDING CODE same DTC present?

Yes

Replace PCM, then go to the next step.

(See PCM REMOVAL/INSTALLATION [AJ (3.0L Duratec)].)

No

Go to the next step.

27
VERIFY AFTER SERVICE PRECAUTION
• Perform "AFTER SERVICE PRECAUTION".

(See AFTER SERVICE PRECAUTION [AJ (3.0L Duratec)].)

• Is there any DTC present?

Yes

Go to applicable DTC inspection.

(See DTC TABLE [AJ (3.0L Duratec)].)

No

Troubleshooting completed.

STEP	INSPECTION		ACTION
1	VERIFY FREEZE FRAME DATA HAS BEEN RECORDED • Has FREEZE FRAME DATA been recorded?	Yes	Go to the next step.
1		No	Record the FREEZE FRAME DATA on the repair order, then go to next step.
2	VERIFY REPAIR INFORMATION AVAILABILITY • Verify related service repair information availability. • Is any related repair information available?	Yes	Perform repair or diagnosis according to the available repair information. • If the vehicle is not repaired, go to the next step.
2		No	Go to the next step.
3	CHECK FOR ADAPTIVE FUEL MONITOR AND HO2S CONTINUOUS MEMORY DTCS Note • Following is a list of non-misfire DTCs to look for in the Continuous Memory. • Retrieve the continuous memory DTC from PCM. • Are any of DTCs P0136, P0156, P0171, P0172, P0174, P0175, P1130 and/or P1150 displayed?	Yes	Go to Step 5.
3		No	Go to the next step.
4	CHECK FOR OTHER NON-MISFIRE CONTINUOUS MEMORY DTCS Note • Following is a list of non-misfire DTCs to look for in the Continuous Memory. • Are other non-misfire DTCs present?	Yes	Go to applicable DTC inspection. (See DTC TABLE [AJ (3.0L Duratec)].)
4		No	Go to the next step.
5	CKECK FOR KEY ON ENGINE OFF (KOEO) SELF TEST • Perform the KOEO self test. • Are any KOEO DTCs displayed?	Yes	Go to applicable DTC inspection. (See DTC TABLE [AJ (3.0L Duratec)].)
5		No	Inspect spark plugs and ignition coil. If okay, go to the next step.
6	CHECK FOR OTHER KEY ON ENGINE RUNNING (KOER) SELF EST Note • Check any KOER DTCs, which can cause the Misfire DTC. • Perform the KOER self test. • Are any additional KOER DTCs displayed?	Yes	If the DTCs P1132, P1138, P1152, P1158, P1131, P1137, P1151 or P1157 are present: Go to Step 9. All others: Go to applicable DTC inspection. (See DTC TABLE [AJ (3.0L Duratec)].)
6		No	Go to the next step.
7	CHECK/COMPARE PID VALUES • Start the engine and warm up to normal operating temperature. • Access DPFEGR PID. • Record DPFEGR PID value. • Turn the ignition switch to OFF. • Turn the ignition switch to ON. • Access DPFEGR PID. • Compare ignition switch ON position (engine off) and idle PID values. • Was the idle PID value within 0.15 V of ignition switch ON position (engine off) value?	Yes	Go to the next step.
7		No	Go to Step 25.
8	EGR RESTRICTION/FLOW TEST Note • Check any KOER DTCs, which can cause the Misfire DTC. • Record and clear DTCs. • Disconnect the vacuum line at EGR valve and plug the vacuum line. • Complete Misfire Monitor Drive Mode. • Is P0300 still present?	Yes	Go to the next step.
8		No	Inspect for the intake manifold and the EGR valve, then go to Step 26.
9	CHECK INJECTOR DRIVER PIDS INJ1F THROUGH INJ6F • Turn the ignition switch ON. • Access INJ1F, INJ2F, INJ3F, INJ4F, INJ5F and INJ6F PIDs. • Are the PIDs status Yes?	Yes	Go to the next step.
9		No	Go to Step 11.
10	CHECK FUEL INJECTORS AND HARNESSES FOR OPEN • Disconnect PCM. • Measure resistance following at PCM harness side connector. - Between terminal 75 (R.H.D.) /E-2 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (for fuel injector No.1) - Between terminal 101 (R.H.D.) /E-5 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (for fuel injector No.2) - Between terminal 74 (R.H.D.) /E-13 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (for fuel injector No.3) - Between terminal 100 (R.H.D.) /E-4 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (for fuel injector No.4) - Between terminal 73 (R.H.D.) /E-3 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (for fuel injector No.5) - Between terminal 99 (R.H.D.) /E-15 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (for fuel injector No.6) • Is the resistance 10-18 ohms?	Yes	Replace the PCM, then go to Step 26.
10		No	Go to Step 21.
11	CHECK FUEL PRESSURE • Install fuel pressure gauge. • Start and run the engine at idle. • Record fuel pressure. • Increase engine speed to 2,500 rpm and maintain for 1 min. • Note and compare fuel pressure. • Is the fuel pressure at the specified pressure? (See FUEL LINE PRESSURE INSPECTION [AJ (3.0L Duratec)].)	Yes	Go to the next step.
11		No	Repair or replace malfunctioning part, then go to Step 26.
12	CHECK ABILITY OF FUEL SYSTEM TO HOLD FUEL PRESSURE • Start and run engine at idle. Note the pressure. • Increase engine speed to 2,500 rpm and maintain for 1 min. • Look for fuel leakage at the fuel injector O-ring, fuel pressure regulator, and the fuel lines to the fuel charging assembly. • Did fuel pressure remain at specification within 34 kPa {5 psi} for 1 min.	Yes	Go to the next step.
12		No	Repair or replace malfunctioning part, then go to Step 26.
13	CHECK FUEL INJECTOR FOR FLOW AND LEAKAGE • Measure the flow rate for each fuel injector (See FUEL INJECTOR INSPECTION [AJ (3.0L Duratec)].) • Is flow rate for each fuel injector within specification?	Yes	Fuel delivery system is not likely to have caused the Misfire DTC. Go to the next step.
13		No	Replace or clean inoperative fuel injector, then go to Step 26.
14	CHECK VACUUM SYSTEM Note • Some vacuum leaks can be heard. • Inspect for all vacuum lines for damage, such as pinched lines, cracks, proper routing and assembly. • Is the vehicle vacuum system okay?	Yes	Go to the next step.
14		No	Repair or replace malfunctioning part, then go to Step 26.
15	CHECK DAMPER AND PULLEY ASSEMBLY Note • This pinpoint step is for engines that have damper mounted pulse rings. Remove the front cover if necessary to observe the crankshaft pulley. • Observe the crankshaft pulley for wobble. • Examine the EI pulse ring fastened to the harmonic fastener. • Does the crank pulley wobble or is pulse ring loose or damaged?	Yes	Replace the pulley or damper assembly, disconnect battery for 5 min to allow PCM to learn mew data. Then go to Step 26.
15		No	Go to the next step.
16	CHECK EVAPORATIVE EMISSION SYSTEM Note • The misfire monitor can be influenced by evaporative emission system. The next five pinpoint test steps will diagnose the evaporative emission system. • Check the charcoal canister for fuel saturation. • Is there an excess amount of liquid fuel present in the fuel vapor storage charcoal canister?	Yes	Repair or replace malfunctioning part, then go to Step 26.
16		No	Go to the next step.
17	CHECK VACUUM IN EVAPORATIVE EMISSION SYSTEM SOLENOID VALVE • Check for blockage/restrictions or cut hose between engine vacuum port and charcoal canister. • Check for blockage in fuel tank vent system. • Is there a fault indicated?	Yes	Repair or replace malfunctioning part, then go to Step 26.
17		No	Go to the next step.
18	CHECK OF PURGE SOLENOID VALVE HOUSING LEAKS • Purge solenoid valve electrically connected. • Install a hand vacuum pump to the vapor port from charcoal canister on the purge solenoid valve vacuum at line. • Apply 53 kPa {16 in Hg} of vacuum with the vacuum pump. • Does the purge solenoid valve hold vacuum at room temperature?	Yes	Go to the next step.
18		No	Replace purge solenoid valve, then go to Step 26.
19	CHECK FOR FILTER CONTAMINATION ON DAMAGE PURGE SOLENOID VALVE • Vacuum line from input vacuum port to intake manifold on the purge solenoid valve (control vacuum solenoid part of valve) removed. • Install a hand held vacuum pump to the open input vacuum port on the purge solenoid valve. • Apply 48-52kPa {10-15 inHg} of vacuum to the purge solenoid valve. • Does the purge solenoid valve hold vacuum, or is the valve very slow to release vacuum to atmosphere?	Yes	Replace purge solenoid valve filter. If unable to clean filter or remove blockage to filter, replace purge solenoid valve. Then go to Step 26.
19		No	Go to the next step.
20	CHECK FOR BASE ENGINE CONCERNS Note • This pinpoint test step will determine if there are any base engine concerns the may have caused the misfire DTC or drive concern. • Engine temperature may affect results. • Perform the following tests in order to evaluate base engine integrity: - Compression and leak down test - Valve train analysis - PCV system - Possible leakage points • Is any service required?	Yes	Overhaul the engine. (See ENGINE WORKSHOP MANUAL.) Then go to Step 26.
20		No	Intermittent concern exist, then go to Step 26.
21	CHECK FUEL INJECTOR HARNESS RESISTANCE • Disconnect the malfunctioning fuel injector in Step 10. • Measure the resistance for following at harness side connector: - Between fuel injector No.1 terminal 2 and PCM terminal 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ1F, P0201) - Between fuel injector No.1 terminal 1 and PCM terminal 75 (R.H.D.) /E-2 (L.H.D.) (INJ1F, P0201) - Between fuel injector No.2 terminal 2 and PCM terminal 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ2F, P0202) - Between fuel injector No.2 terminal 1 and PCM terminal 101 (R.H.D.) /E-5 (L.H.D.) (INJ2F, P0202) - Between fuel injector No.3 terminal 2 and PCM terminal 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ3F, P0203) - Between fuel injector No.3 terminal 1 and PCM terminal 74 (R.H.D.) /E-13 (L.H.D.) (INJ3F, P0203) - Between fuel injector No.4 terminal 2 and PCM terminal 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ4F, P0204) - Between fuel injector No.4 terminal 1 and PCM terminal 100 (R.H.D.) /E-4 (L.H.D.) (INJ4F, P0204) - Between fuel injector No.5 terminal 2 and PCM terminal 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ5F, P0205) - Between fuel injector No.5 terminal 1 and PCM terminal 73 (R.H.D.) /E-3 (L.H.D.) (INJ5F, P0205) - Between fuel injector No.6 terminal 2 and PCM terminal 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ6F, P0206) - Between fuel injector No.6 terminal 1 and PCM terminal 99 (R.H.D.) /E-15 (L.H.D.) (INJ6F, P0206) • Is each resistance less than 5.0 ohms?	Yes	Go to the next step.
21		No	Repair for open circuit, then go to Step 26.
22	CHECK FUEL INJECTOR HARNESS CIRCUIT FOR SHORT TO POWER AND GROUND • Disconnect PCM. • Malfunctioning fuel injector in Step 10 disconnected. • Measure resistance for following at PCM harness side connector. - Terminal 75 (R.H.D.) /E-2 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ1F, P0201) - Terminal 75 (R.H.D.) /E-2 (L.H.D.) and 24, 51, 76, 103 (R.H.D.) /C-48, C-49 (L.H.D.) (INJ1F, P0201) - Terminal 101 (R.H.D.) /E-5 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ2F, P0202) - Terminal 101 (R.H.D.) /E-5 (L.H.D.) and 24, 51, 76, 103 (R.H.D.) /C-48, C-49 (L.H.D.) (INJ2F, P0202) - Terminal 74 (R.H.D.) /E-13 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ3F, P0203) - Terminal 74 (R.H.D.) /E-13 (L.H.D.) and 24, 51, 76, 103 (R.H.D.) /C-48, C-49 (L.H.D.) (INJ3F, P0203) - Terminal 100 (R.H.D.) /E-4 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ4F, P0204) - Terminal 100 (R.H.D.) /E-4 (L.H.D.) and 24, 51, 76, 103 (R.H.D.) /C-48, C-49 (L.H.D.) (INJ4F, P0204) - Terminal 73 (R.H.D.) /E-3 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ5F, P0205) - Terminal 73 (R.H.D.) /E-3 (L.H.D.) and 24, 51, 76, 103 (R.H.D.) /C-48, C-49 (L.H.D.) (INJ5F, P0205) - Terminal 99 (R.H.D.) /E-15 (L.H.D.) and 71, 97 (R.H.D.) /C-35, C-36 (L.H.D.) (INJ6F, P0206) - Terminal 99 (R.H.D.) /E-15 (L.H.D.) and 24, 51, 76, 103 (R.H.D.) /C-48, C-49 (L.H.D.) (INJ6F, P0206) • Is each resistance greater than10,000 ohms?	Yes	Go to the next step.
22		No	Repair for short circuit, then go to Step 26.
23	INSPECT FUEL INJECTOR(S) • Inspect fuel injectors. (See FUEL INJECTOR INSPECTION [AJ (3.0L Duratec)].) • Are fuel injectors okay?	Yes	Go to the next step.
23		No	Replace suspected fuel injector, then go to Step 26.
24	INSPECT INDUCTION SYSTEM FOR AIR LEAKS • Inspect the following areas for signs of air leaks: - Inlet tube(s) from air cleaner to throttle body - Gaskets which seal the upper and lower intake manifold. - Vacuum hoses and lines for cranks and proper connections. - PCV system. • Are there any signs of leaks or damage?	Yes	Repair or replace malfunctioning part, then go to Step 26.
24		No	Intermittent malfunction exist, go to the Step 26.
25	CHECK FOR EGR FLOW WITH EGR VACUUM HOSE DISCONNECTED AND PLUGGED • Disconnect vacuum hose at EGR valve and plug hose. • Connect the WDS or equivalent to DLC. • Turn then ignition switch to ON. • Access DPFEGR PID and note PID value. • Start the engine and bring idle. • With engine at idle, look at the DPFEGR PID value and compare to the engine off reading. An increase in the PID value at idle indicates that the D.P.F.EGR sensor is sensing EGR flow. • Is the DPFEGR PID value greater at idle by a minimum of 0.15 V than with the engine off?	Yes	Remove and inspect the EGR valve for signs of contamination, unusual wear, carbon deposits, binding and other damage. Repair or replace the EGR valve, according to inspection result. Then go to the next step.
25		No	Inspect the EGR solenoid valve and solenoid valve filter for restrictions. Repair or replace malfunctioning part, then go to the next step.
26	VERIFY TROUBLESHOOTING OF DTC P0300 COMPLETED • Make sure to reconnect all disconnected connectors. • Clear the DTC from the PCM memory using the WDS or equivalent. • Perform KOER self test. (See KOEO/KOER SELF-TEST [AJ (3.0L Duratec)].) • Is the PENDING CODE same DTC present?	Yes	Replace PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION [AJ (3.0L Duratec)].)
26		No	Go to the next step.
27	VERIFY AFTER SERVICE PRECAUTION • Perform "AFTER SERVICE PRECAUTION". (See AFTER SERVICE PRECAUTION [AJ (3.0L Duratec)].) • Is there any DTC present?	Yes	Go to applicable DTC inspection. (See DTC TABLE [AJ (3.0L Duratec)].)
27		No	Troubleshooting completed.