Mazda 6. Manual - part 150

F–122

ON-BOARD DIAGNOSTIC 

5

VERIFY CURRENT INPUT SIGNAL STATUS 
UNDER TROUBLE CONDITION

• Inspect same PIDs as in Step 4 while 

simulating FREEZE FRAME DATA condition.

• Is there any signal which causes drastic 

changes?

Yes Inspect suspected circuit and/or part according to 

inspection results.
(See 

F–45 PCM INSPECTION

.)

Then go to Step 22.

No

Go to next step.

6

INSPECT CMP SENSOR

• Inspect CMP sensor.

(See 

F–55 CAMSHAFT POSITION (CMP) 

SENSOR INSPECTION

.)

• Is CMP sensor okay?

Yes Go to next step.

No

Inspect installation condition and damages on timing belt 
and gears, repair faulty parts.

• If it is okay, replace CMP sensor.

Then go to Step 22.

7

VERIFY CKP SENSOR INSTALLATION 
CONDITION

• Inspect for CKP sensor looseness.

• Is CKP sensor loosen?

Yes Retighten CKP sensor, then go to Step 22.

No

Go to next step.

8

INSPECT IGNITION COIL OPERATION AND 
HIGH-TENSION LEAD WITH TIMING LIGHT

• Verify blinking condition on each cylinders 

using timing light at idle.

• Do all cylinders show blinking condition?

Yes Go to Step 12.

No

Go to next step.

9

INSPECT HIGH-TENSION LEADS OF NO 
BLINKING CYLINDER

• Turn ignition key to OFF.

• Inspect high-tension leads for improper 

installation, corrosion on terminal, open lead 
and damaged cover.

• Is condition of high-tension lead okay?

Yes Go to next step.

No

Replace faulty high-tension lead, then go to Step 22.

10

INSPECT POWER SUPPLY TERMINAL AT 
IGNITION COIL CONNECTOR

• Disconnect ignition coil connector.

• Turn ignition key to ON (Engine OFF).

• Measure voltage between ignition coil terminal 

B (harness-side) and body ground.

• Is there voltage reading B+?

Yes Go to next step.

No

Inspect for open circuit between ignition coil connector and 
ignition switch. Repair or replace wiring harness, then go to 
Step 22.

11

INSPECT IGNITION COIL RESISTANCE

• Inspect ignition coil resistance.

(See 

G–9 IGNITION COIL INSPECTION

.)

• Is coil resistance okay?

Yes Go to step 22.

No

Replace ignition coil, then go to Step 22.

12

INSPECT MAF PID

• Start engine.

• Access MAF PID using WDS or equivalent.

• Verify that MAF PID changes quickly according 

to race engine RPM.

• Is MAF PID response okay?

Yes Go to next step.

No

Replace MAF sensor, then go to Step 22.

13

INSPECT EXCESSIVE AIR SUCTION IN INTAKE 
AIR SYSTEM

• Inspect for air leakage at following:

— Between MAF sensor and throttle body
— Between throttle body and intake manifold

• Is there any malfunction?

Yes Repair or replace suspected part, then go to Step 22.

No

Go to next step.

14

INSPECT FUEL LINE PRESSURE

• Inspect fuel line pressure.

(See 

F–20 FUEL LINE PRESSURE 

INSPECTION

.)

• Is fuel line pressure okay?

Yes Go to step 16.

No

If fuel line pressure is too low, go to next step.
If fuel line pressure is excess high, replace fuel pump unit, 
then go to Step 22.

STEP

INSPECTION

ACTION

ON-BOARD DIAGNOSTIC 

F–123

F

15

INSPECT FUEL LINE FROM FUEL PUMP TO 
FUEL DELIVERY PIPE

• Visually inspect for fuel leakage in fuel line for 

any leakage.

• Is any fuel leakage found?

Yes Replace suspected fuel line, then go to Step 22.

No

Inspect fuel filters for following:

• Restriction or clogging at fuel filter (high-pressure side).

• Foreign materials or stain inside fuel filter (low-pressure 

side)

Perform following actions depend on the result above.

• If restriction or clogging is found at fuel filter (high-

pressure side), replace fuel pump unit.

• If foreign materials or stain is found inside fuel filter 

(low-pressure side), clean of fuel tank and filter (low-
pressure side).

• If all items above are okay, replace fuel pump unit.

Then, go to Step 22.

16

INSPECT ENGINE COMPRESSION

• Inspect engine compression.

(See 

B–9 COMPRESSION INSPECTION

.)

• Is it okay?

Yes Go to next step.

No

Implement engine overhaul for repairs, then go to Step 22.

17

INSPECT VARIABLE VALVE TIMING CONTROL 
SYSTEM OPERATION

Note

• The following test should be performed for 

variable valve timing control system. Go to 
next step for vehicles without variable valve 
timing control system.

• Inspect variable valve timing control system 

operation.

• Does variable valve timing control system?

Yes Go to next step.

No

Repair or replace malfunctioning part according to variable 
valve timing control system inspection results, then go to 
Step 22.

18

INSPECT OPERATION OF PURGE CONTROL 
SOLENOID VALVE

• Turn ignition key to OFF.

• Connect vacuum pump to purge control 

solenoid valve and apply vacuum to solenoid.

• Verify that solenoid holds vacuum.

• Turn ignition key to ON (Engine OFF).

• Access EVAPCP PID in SIMULATION TEST 

using WDS or equivalent.

• Set duty value to 100% for EVAPCP PID.

• Apply vacuum while turning solenoid from OFF 

to ON and simulating EVAPCP PID with 100% 
duty value.

• Verify that solenoid releases vacuum while 

solenoid is turned ON.

• Is purge control solenoid valve operation okay?

Yes Go to next step.

No

Replace purge control solenoid valve, then go to Step 22.

19

INSPECT PCV VALVE OPERATION

• Turn ignition key to OFF.

• Remove PCV valve and inspect valve 

operation.
(See 

F–41 PCV VALVE INSPECTION

.)

• Is PCV valve operation okay?

Yes Replace PCV valve, then go to Step 22.

No

Go to next step.

20

INSPECT OPERATION OF EGR VALVE

• Remove EGR valve.

• Visually inspect for stuck to open.

• Does EGR valve stuck to open?

Yes Repair or replace EGR valve, then go to Step 22.

No

Go to next step.

STEP

INSPECTION

ACTION

F–124

ON-BOARD DIAGNOSTIC 

End Of Sie

DTC P0301, P0302, P0303, P0304

A6E397001085W02

21

INSPECT SEALING OF ENGINE COOLANT 
PASSAGE

Warning
• Removing radiator cap when radiator is 

hot is dangerous. Scalding coolant and 
steam may shoot out and cause serious 
injury.

• When removing radiator cap, wrap thick 

cloth around and turn it slowly.

• Remove radiator cap.

• Implement procedure to bleed air from engine 

coolant, then run engine at idle.

• Is there any small bubble which makes engine 

coolant white at filling opening?

Note

• Large bubbles are normal since they are 

remaining air coming out from engine 
coolant passage.

Yes Air gets in from poor sealing on head gasket or other areas 

between combustion chamber and engine coolant 
passage. Repair or replace faulty parts, then go to next 
step.

No

Go to next step.

22

VERIFY TROUBLESHOOTING OF MISFIRE DTC 
COMPLETED

• Make sure to reconnect all disconnected 

connectors.

• Turn ignition key to ON (Engine OFF).

• Clear DTC from memory using WDS or 

equivalent.

• Run PCM adaptive memory procedure drive 

mode.
(See 

F–64 OBD DRIVE MODE

.)

• Is PENDING CODE the same as DTC 

present?

Yes Replace PCM, then go to next step.

(See 

F–43 PCM REMOVAL/INSTALLATION

.)

No

Go to next step.

23

VERIFY AFTER REPAIR PROCEDURE

• Perform “After Repair Procedure”.

(See 

F–66 AFTER REPAIR PROCEDURE

.)

• Is there any DTC present?

Yes Go to applicable DTC troubleshooting.

(See 

F–67 DTC TABLE

.)

No

Troubleshooting completed.

STEP

INSPECTION

ACTION

DTC P0301
DTC P0302
DTC P0303
DTC P0304

Cylinder No.1 misfire detection
Cylinder No.2 misfire detection
Cylinder No.3 misfire detection
Cylinder No.4 misfire detection

DETECTION 

CONDITION

• PCM monitors CKP sensor input signal interval time. PCM calculates the change of interval time for each 

cylinder. If the change of interval time exceeds the preprogrammed criteria, PCM detects a misfire in the 
corresponding cylinder. While the engine is running, PCM counts number of misfires that occurred at 200 
crankshaft revolutions and 1,000 crankshaft revolutions and calculates misfire ratio for each 
crankshaft revolution. If the ratio exceeds the preprogrammed criteria, PCM determines that a misfire, 
which can damage catalytic converter or affect emission performance, has occurred.

Diagnostic support note

• This is a continuous monitor (MISFIRE).

• MIL illuminates if PCM detects the misfire which affects emission performance in two consecutive drive 

cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.

• MIL flashes if PCM detects the misfire which can damage the catalytic converter during first drive cycle.   

Therefore, PENDING CODE is not available while MIL flashes.

• PENDING CODE is available if PCM detects the misfire which affects emission performance during first 

drive cycle.

• FREEZE FRAME DATA is available.

• DTC is stored in the PCM memory.

POSSIBLE 

CAUSE

• Spark plug malfunction

• High-tension lead malfunction

• Fuel injector malfunction

• Air suction in intake air system (between dynamic chamber and cylinder head)

• Inadequate engine compression due to engine internal malfunction

• Related connector or terminal malfunction

• Related wiring harness malfunction

ON-BOARD DIAGNOSTIC 

F–125

F

Diagnostic procedure

STEP

INSPECTION

ACTION

1

VERIFY FREEZE FRAME DATA HAS BEEN 
RECORDED

• Has FREEZE FRAME DATA been recorded?

Yes Go to next step.

No

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

2

VERIFY RELATED SERVICE INFORMATION 
AVAILABILITY

• Check for related Service Information 

availability.

• Is any related Service Information available?

Yes Perform repair or diagnosis according to available Service 

Information.

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

No

Go to next step.

3

VERIFY RELATED PENDING CODE OR 
STORED DTCS

• Turn ignition key to OFF then ON (Engine 

OFF).

• Verify related pending code or stored DTCs.

• Is other DTCs present?

Yes Go to appropriate DTC troubleshooting. 

(See 

F–67 DTC TABLE

.)

No

Go to next step.

4

VERIFY CURRENT INPUT SIGNAL STATUS 
(IGNITION KEY TO ON /IDLE)

• Access BOO, ECT, IAT, MAF, RPM, TP and 

VSS PIDs using WDS or equivalent.
(See 

F–45 PCM INSPECTION

.)

• Is there any signal that is far out of 

specification when ignition switch is ON and 
engine runs at idle?

Yes Inspect suspected circuit and/or part according to 

inspection results. Then go to Step 12.
(See 

F–45 PCM INSPECTION

.)

No

Go to next step.

5

VERIFY CURRENT INPUT SIGNAL STATUS 
UNDER TROUBLE CONDITION

• Inspect same PIDs as in Step 4 while 

simulating FREEZE FRAME DATA condition.

• Is there any signal which causes drastic 

changes?

Yes Inspect suspected circuit and/or part according to 

inspection results. Then go to Step 12.
(See 

F–45 PCM INSPECTION

.)

No

Go to next step.

6

INSPECT SPARK PLUG CONDITION

• Turn ignition key to OFF.

• Remove spark plug from suspected cylinder.

• Inspect spark plug condition:

— Cracks
— Excess wear
— Gap
— Wet

• Is any problem found on spark plug?

Yes

• If spark plug is wet, fuel flooding is suspected. Go to 

step 12.

• If spark plug has a cracks, excessive wear or improper 

gap, replace faulty spark plug. Then go to Step 12. 

No

Go to next step.

7

VERIFY HIGH-TENSION LEAD CONDITION

• Remove high-tension lead.

• Inspect high-tension lead condition and 

resistance.
— Cracks
— Spark shorts to cylinder head through high-

tension lead insulator

• Is high-tension lead okay? 

Yes Go to next step.

No

Replace high-tension lead, then go to Step 12.

8

INSPECT FOR AIR SUCTION AT INTAKE-AIR 
SYSTEM

• Inspect for air leakage at following:

— Around connection of dynamic chamber and 

intake manifold

— Around connection of intake manifold and 

cylinder head

• Is air leakage found?

Yes Repair or replace suspected part, then go to Step 12.

No

Go to next step.

9

INSPECT FUEL INJECTOR HARNESS

• Remove intake air system parts.

• Disconnect fuel injector connector on 

suspected cylinder.

• Connect NOID LIGHT to fuel injector connector 

terminals.

• Inspect dim of light during cranking.

• Does noid light illuminate?

Yes Go to next step.

No

Inspect for fuel injector harnesses.
Repair or replace it if necessary, then go to Step 12.