Mazda 6. Manual - part 167

F–190

TROUBLESHOOTING 

End Of Sie

6

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.

7

Measure gap between CKP sensor and teeth of 
crankshaft pulley.

Specification

0.5—1.9 mm {0.020—0.75 in}

Is gap within specification?

Yes

Go to next step.

No

Adjust CKP sensor.

8

Remove and shake PCV valve.
Does PCV valve rattle?

Yes

Go to next step.

No

Replace PCV valve.

9

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 with ignition switch 
ON?
(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.

10

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.

11

Disconnect a vacuum hose from purge solenoid 
valve and plug opening end of vacuum hose. 
Attempt to start engine.
Is starting condition improved?

Yes

Inspect if purge solenoid valve sticks open.

No

Go to next step.

12

Inspect MAF sensor for contamination.
Is there any contamination?

Yes

Replace MAF sensor.

No

Go to next step.

13

Is there restriction in exhaust system?

Yes

Inspect exhaust system.

No

Go to next step.

14

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

Yes

Replace EGR valve.

No

Go to next step.

15

Inspect starting system.
(See 

G–12 STARTER INSPECTION

.)

Is starting system normal?

Yes

Inspect for loose connectors or poor terminal contact. If 
okay, remove EGR valve and visually inspect for 
mechanically stuck EGR valve.

No

Repair or replace components as required.

16

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–191

F

NO.5 ENGINE STALLS-AFTER START/AT IDLE

A6E398018881W07

Diagnostic procedure

5

ENGINE STALLS—AFTER START/AT IDLE

DESCRIPTION

• Engine stops unexpectedly.

POSSIBLE CAUSE

• A/C system operation is improper

• Air leakage from intake-air system parts

• Purge solenoid valve malfunction

• Improper operation of IAC valve

• EGR valve malfunction

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

• Vacuum leakage

• Engine overheating

• Low engine compression

• Spark leakage from high-tension leads

• Poor fuel quality

• PCV valve malfunction

• Air cleaner restriction

• Restriction in exhaust system

• Electrical connector disconnection

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

• No battery power supply to PCM or poor GND

• Inadequate fuel pressure

• Fuel pump body mechanical malfunction

• Fuel leakage from fuel injector

• Fuel injector clogging

• Ignition coil malfunction

• Improper air/fuel mixture ratio control

• Improper valve timing

• Improper operation variable valve timing control system (L3-VE)

• 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

• The 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 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 systemis okay.
Go to Step 10.

3

Is coil connector securely connected to coil?

Yes

Go to next step.

No

Connect coil connector securely.
Return to Step 2.

F–192

TROUBLESHOOTING 

4

Does security light illuminate?

Yes

Go to next step.

No

Inspect instrument cluster and wiring harness.

5

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

DTC

B1213, B1342, B1600, 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

Inspection 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

• Air cleaner element

• No air leakage from intake-air system

• No restriction of intake-air system

• Proper sealing of intake manifold and 

components attached to intake manifold:
EGR valve, IAC valve

• Ignition wiring

• Fuel quality: proper octane, contamination, 

winter/summer blend

• Electrical connections

• Smooth operation of throttle valve

Are all items okay?

Yes

Go to next step.

No

Service as necessary.
Repeat Step 10.

11

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

Voltage

4.5—5.5 V

Is voltage okay?

Yes

Go to next step.

No

Go to troubleshooting "No.27 Constant voltage".

12

Connect WDS or equivalent to DLC-2.
Retrieve any continuous memory, KOEO and 
KOER DTCs.
If engine stalls, retrieve continuous memory and 
KOEO DTCs.
Are there any DTC 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.

13

Attempt to start engine at part throttle.
Does engine run smoothly at part throttle?

Yes

Inspect IAC valve and wiring harness.

No

Go to next step.

STEP

INSPECTION

RESULTS

ACTION

TROUBLESHOOTING 

F–193

F

14

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

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 2C or 2D

• Open or short circuit in CKP sensor harnesses

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

15

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.

16

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.

17

Inspect for cracks on high-tension leads.
Are there any cracks on high-tension leads?

Yes

Repair suspected high-tension leads.

No

Go to next step.

18

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

Yes

Go to next step.
If symptom occurs with A/C on, go to Step 24.

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 body GND

• Open circuit between ignition switch and ignition 

coil

• Open circuit between ignition coil and PCM 

terminal 1A or 1B

19

Inspect spark plug condition.
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.

20

Remove and shake PCV valve.
Does PCV valve rattle?

Yes

Go to next step.

No

Replace PCV valve.

21

Inspect for restriction in the exhaust system.
Is there any restriction?

Yes

Inspect exhaust system.

No

Go to next step.

22

Install fuel pressure gauge between fuel pipe 
and fuel distributor.
Connect 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 with ignition switch 
ON?
(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.

23

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.

STEP

INSPECTION

RESULTS

ACTION