Mazda 6. Manual - part 168

F–194

TROUBLESHOOTING 

End Of Sie

24

Note

• Following test is for stall concerns with A/

C on. If other symptoms exist, go to next 
step.

Connect pressure gauges to A/C low and high 
pressure side lines.
Turn A/C on and measure low side and high side 
pressures.
Are pressures within specifications?
(See 

U–12 REFRIGERANT PRESSURE 

CHECK

.)

Yes

Go to next step.

No

If A/C is always on, go to symptom troubleshooting 
"No.24 A/C is always on  or A/C compressor runs 
continuously".
For other symptoms, inspect following:

• Refrigerant charging amount

• Condenser fan operation

25

Disconnect vacuum hose between purge 
solenoid valve and intake manifold from purge 
solenoid side. 
Plug opening end of vacuum hose.
Start engine.
Is engine stall now eliminated?

Yes

Inspect if purge solenoid valve sticks open.
Inspect evaporative emission control system.

No

Go to next step.

26

Is air leakage felt or heard at intake-air system 
components while racing engine to higher 
speed?

Yes

Repair or replace.

No

Go to next step.

27

Inspect engine condition while tapping EGR 
valve housing.
Does engine condition improve?

Yes

Replace EGR valve.

No

Go to next step.

28

Note

• The following test should be performed for 

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

Inspect variable valve timing control system 
operation.
(See 

F–239 Variable Valve Timing Control 

System Operation Inspection

.)

Does variable valve timing control work 
properly?

Yes

Go to next step.

No

Repair or replace malfunctioning parts.

29

Is engine compression correct?

Yes

Inspect valve timing.

No

Inspect for cause.

30

Verify test results.

• If okay, return to diagnostic index to service any additional symptoms.

• If malfunction remains, replace PCM.

STEP

INSPECTION

RESULTS

ACTION

TROUBLESHOOTING 

F–195

F

NO.6 CRANKS NORMALLY BUT WILL NOT START

A6E398018881W08

Diagnostic procedure

6

CRANKS NORMALLY BUT WILL NOT START

DESCRIPTION

• Starter cranks engine at normal speed but engine will not run.

• Refer to symptom troubleshooting "No.5 Engine stalls" if this symptom appears after engine stall.

• Fuel is in tank.

• Battery is in normal condition.

POSSIBLE CAUSE

• No battery power supply to PCM

• Air leakage from intake-air system

• Open PCM GND or vehicle body GND

• Improper operation of IAC valve

• EGR valve malfunction

• No signal from CKP sensor due to sensor, related wire or incorrect installation

• No signal from CMP sensor due to sensor, related wire or incorrect installation

• Low engine compression

• Engine overheating

• Vacuum leakage

• Spark leakage from high-tension leads

• Improper air/fuel mixture ratio control

• Poor fuel quality

• PCV valve malfunction

• Air cleaner restriction

• Restriction in exhaust system

• Disconnected electrical connector

• Open or short circuit in fuel pump body and related harness

• Inadequate fuel pressure

• Fuel pump mechanical malfunction

• Fuel leakage from injector

• Fuel injector is clogged.

• Purge solenoid valve malfunction

• Spark plug malfunction

• Ignition coil malfunction

• Improper variable valve timing control system operation (L3)

• Improper valve timing

• Immobilizer system (PATS) and/or circuit malfunction (if equipped)

• Pressure regulator malfunction

Warning
The following troubleshooting flow chart contains the fuel system diagnosis and repair 
procedures. Read the following warnings before performing the fuel system services:

• Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always 

keep sparks and flames away from fuel.

• Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or 

death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete 
"BEFORE REPAIR PROCEDURE" and "AFTER REPAIR PROCEDURE" described in this 
manual.
(See 

F–17 BEFORE REPAIR PROCEDURE

.)

(See 

F–17 AFTER REPAIR PROCEDURE

.)

Caution

• Disconnecting/connecting quick release connector without cleaning it may possibly cause 

damage to fuel pipe and quick release connector. Always clean quick release connector 
joint area before disconnecting/connecting, and make sure that it is free of foreign material.

STEP

INSPECTION

RESULTS

ACTION

1

Note

• Following test should be performed for 

vehicles with immobilizer system. Go to 
Step 10 for vehicles without immobilizer 
system.

Connect WDS or equivalent to DLC-2.
Do any of following conditions appear?

• Engine is not completely started.

• DTC B1681 is displayed.

Yes

Both conditions appear:
Go to Step 3.

No

Either or other condition appears:
Go to next step.

2

Does engine stall after approx. 2 seconds since 
engine is started?

Yes

Go to next step.

No

Immobilizer system is okay.
Go to Step 10.

F–196

TROUBLESHOOTING 

3

Is coil connector securely connected to coil?

Yes

Go to next step.

No

Connect coil connector securely.
Return to Step 2.

4

Does security light illuminate?

Yes

Go to next step.

No

Inspect instrument cluster and wiring harness.

5

Connect WDS equivalent to DLC-2 and retrieve 
DTC.
Are any of following DTCs displayed?

DTC

B1213, B1342, B1600, B1601, B1602, B1681, 

B2103, B2431

Yes

Go to appropriate DTC test.

No

Go to next step.

6

Is there continuity between PCM GND terminals 
4X, 2AB, 2AC and GND?

Yes

Go to next step.

No

Repair or replace wiring harness.

7

Measure voltage between PCM GND terminals 
4X, 2AB, 2AC and coil terminal C.
Is voltage below 1.0 V?

Yes

Go to next step.

No

Repair or replace wiring harness.

8

Turn ignition switch to ON position.
Access VPWR PID.
Is VPWR PID okay?

VPWR PID

Battery voltage

Yes

Go to next step.

No

Repair or replace wiring harness.

9

Disconnect coil connector.
Turn ignition switch to ON position.
Is there battery voltage at coil connector terminal 
D?

Yes

Inspect for following:

• Open or short circuit between coil terminal A and 

PCM terminal 2Q

• Open or short circuit between coil terminal B and 

PCM terminal 2T

No

Repair or replace wiring harness between coil 
connector terminal D and fuse panel.

10

Verify following:

• Vacuum connection

• External fuel shut off or accessory (kill 

switch, alarm etc.)

• Fuel quality: proper octane, contamination, 

winter/summer blend

• No air leakage from intake-air system

• Proper sealing of intake manifold and 

components attached to intake manifold:  
EGR valve, IAC valve

• Ignition wiring

• Electrical connections

• Fuses

• Smooth operation of throttle valve

Are all items okay?

Yes

Go to next step.

No

Service as necessary.
Repeat Step 10.

11

Connect WDS or equivalent to DLC-2.
Retrieve any continuous memory and KOEO 
DTC.
Are there any DTCs displayed?

Yes

DTC is displayed:
Go to appropriate DTC test.
Communication error message is displayed:
Inspect for following:

• Open circuit between main relay and PCM terminal 

2Y or 4V

• Open main relay GND circuit

• Main relay is stuck open.

• Open or poor GND circuit (PCM terminal 4X, 2AB, 

or 2AC)

• Poor connection of vehicle body GND

No

No DTC is displayed:
Go to next step.

12

Turn ignition switch to ON position.
Disconnect TP sensor connector.
Measure voltage at TP sensor connector VREF 
terminal with ignition switch to  ON position.

Voltage

4.5—5.5 V

Is voltage okay?

Yes

Go to next step.

No

Go to troubleshooting "No.27 Constant voltage".

13

Does engine start with throttle closed?

Yes

Go to Step 29.

No

Go to next step.

STEP

INSPECTION

RESULTS

ACTION

TROUBLESHOOTING 

F–197

F

14

Will engine start and run smoothly at part 
throttle? 

Yes

Inspect IAC valve and wiring harness.

No

Go to next step.

15

Connect WDS or equivalent to DLC-2.
Access RPM PID.
Is RPM PID indicating engine speed when 
cranking engine?

Yes

Go to next step.

No

Inspect for following:

• Open or short circuit in CKP sensor

• Open or short circuit between CKP sensor and 

PCM terminal 1A or 1B

• Open or short circuit in CKP sensor harnesses

If CKP sensor and harness are okay, go to next step.

16

Visually inspect CKP sensor and teeth of 
crankshaft pulley.
Are CKP sensor and teeth of crankshaft pulley 
okay?

Yes

Go to next step.

No

Replace malfunctioning parts.

17

Measure gap between CKP sensor and teeth of 
crankshaft pulley.

Specification

0.5—1.9 mm {0.020—0.075 in}

Is gap within specification?

Yes

Go to next step.

No

Adjust CKP sensor.

18

Inspect for cranks on high-tension leads.
Is there any crank on high-tension leads?

Yes

Repair suspected high-tension leads.

No

Go to next step.

19

Is strong blue spark visible at each disconnected 
high-tension lead while cranking engine?

Yes

Go to next step.

No

Inspect for following:

• Open or short circuit in ignition coil

• Open circuit in high-tension leads

• Open circuit between ignition coil connector GND 

terminal and GND

• Open circuit between ignition switch and ignition 

coil

• Open circuit between ignition coil and PCM 

terminal 1A or 1B

20

Inspect spark plug conditions.
Is spark plug wet, covered with carbon or 
grayish white?

Yes

Spark plug is wet or covered with carbon:
Inspect for fuel leakage from injector.
Spark plug is grayish white:
Inspect for clogged fuel injector.

No

Install spark plugs on original cylinders.
Go to next step.

21

Remove and shake PCV valve.
Does PCV valve rattle?

Yes

Go to next step.

No

Replace PCV valve.

22

Inspect for restriction in exhaust system. 

Yes

Inspect exhaust system.

No

Go to next step.

23

Install fuel pressure gauge between fuel pipe 
and fuel distributor.
Connect a jumper wire between F/P terminal at 
DLC-2 in engine compartment and GND.
Turn ignition switch to ON position.
Is fuel line pressure correct when ignition switch 
is turned on/off five times?
(See 

F–20 FUEL LINE PRESSURE 

INSPECTION

)

Yes

Go to next step.

No

Zero or low:
Inspect for clogged fuel line.
If okay, replace fuel pump unit.
High:
Replace fuel pump unit.

24

Visually inspect for fuel leakage at fuel injector 
O-ring and fuel line.
Service as necessary.
Is fuel line pressure held after ignition switch is 
turned off?
(See 

F–20 FUEL LINE PRESSURE 

INSPECTION

)

Yes

Go to next step.

No

Inspect fuel injector.
If fuel injector is okay, replace fuel pump unit.

25

Disconnect vacuum hose between purge 
solenoid valve and intake manifold from  purge 
solenoid valve side.
Plug opening end of vacuum hose.
Attempt to start engine.
Is starting condition improved?

Yes

Inspect if purge solenoid valve sticks open 
mechanically.
Inspect evaporative emission control system.

No

Go to next step.

STEP

INSPECTION

RESULTS

ACTION