Mazda 6. Manual - part 175

F–222

TROUBLESHOOTING 

End Of Sie

NO.26 EXHAUST SULPHUR SMELL

A6E398018881W28

Diagnostic procedure

2

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

Yes

DTC is displayed:
Go to appropriate DTC test.

No

No DTC is displayed:
Inspect TP sensor for proper adjustment.

3

Verify test results.

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

• If malfunction remains, replace PCM.

STEP

INSPECTION

RESULTS

ACTION

26

EXHAUST SULPHUR SMELL

DESCRIPTION

Rotten egg smell (sulphur) from exhaust

POSSIBLE CAUSE

• Electrical connectors are disconnected or connected poorly

• Charcoal canister malfunction

• Vacuum lines are disconnected or connected improperly.

• Improper fuel pressure

• Poor fuel quality

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

Are any driveability or exhaust smoke concerns 
present?

Yes

Go to appropriate flow chart.

No

Go to next step.

2

Inspect following:

• Electrical connections

• Vacuum lines

• Fuel quality

Are all items okay?

Yes

Go to next step.

No

Service as necessary.
Repeat Step 2.

3

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

Yes

DTC is displayed:
Go to appropriate DTC test.

No

No DTC is displayed:
Go to next step.

4

Install fuel pressure gauge between fuel pipe 
and fuel distributor.
Start engine and run it at idle.
Is fuel line pressure correct at idle?
(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.

5

Inspect charcoal canister for fuel saturation.
Is excess amount of liquid fuel present in 
canister?

Yes

Replace charcoal canister.

No

Inspect fuel tank vent system.
If fuel tank vent system is okay, since sulfur content 
can vary in different fuels, suggest trying a different 
brand.
If fuel tank vent system is not okay, repair or  replace 
malfunctioning parts.

6

Verify test results.

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

• If malfunction remains, replace PCM.

TROUBLESHOOTING 

F–223

F

End Of Sie

NO.27 CONSTANT VOLTAGE

A6E398018881W29

Diagnostic procedure

27

CONSTANT VOLTAGE

DESCRIPTION

Incorrect constant voltage

POSSIBLE CAUSE

• Constant voltage circuit malfunction

Note

• TP sensor uses constant voltage.

STEP

INSPECTION

RESULTS

ACTION

1

Disconnect TP sensor connector where constant 
voltage circuit inspection failed.
Turn ignition switch to ON position.
Measure voltage between following TP sensor 
connector terminals:

• Constant voltage terminal - GND terminal

Is constant voltage greater than 6.0 V?

Yes

Go to Step 13.

No

Go to next step.

2

Is voltage across battery terminals greater than 
10.5 V?

Yes

Go to next step.

No

Inspect charging system.

3

Turn ignition switch off.
Leave TP sensor connector disconnected.
Measure voltage between battery positive  
terminal and GND (between PCM and TP  
sensor) circuit at appropriate sensor connector.
Is voltage greater than 10.5 V and within 1.0 V 
of battery voltage?

Yes

Go to next step.

No

Go to Step 8.

4

Note

• Purpose of this step is to determine if 

WDS or equivalent is communicating with 
PCM.

Turn ignition switch to ON position.
Attempt to access ECT PID.
Can ECT PID be accessed?

Yes

Go to Step 7.

No

Go to next step.

5

Turn ignition switch off.
Disconnect TP sensor and PCM connectors.
Turn ignition switch to ON position.
Measure voltage between PCM connector 
terminals 2Y and 2AB.
Is voltage greater than 10.5 V?

Yes

Go to next step.

No

Repair open circuit between PCM terminal 2Y and 
main relay.

6

Leave TP sensor and PCM connectors 
disconnected.
Measure resistance between PCM connector 
terminals 2Y and 2AB.
Is resistance greater than 10,000 ohms?

Yes

Inspect for constant voltage at suspect sensor 
connector again.

No

Repair constant voltage circuit short to GND.

7

Turn ignition switch off.
Leave TP sensor disconnected.
Disconnect PCM connector.
Measure resistance between PCM connector 
terminal 2K and constant voltage circuit at 
appropriate sensor connector.
Is resistance less than 5.0 ohms?

Yes

Inspect for constant voltage at suspect sensor 
connector again.

No

Repair open constant voltage circuit.

8

Note

• Purpose of this step is to determine if 

WDS or equivalent is communicating with 
PCM.

Reconnect TP sensor connector.
Turn ignition switch to ON position.
Attempt to access ECT PID.
Can ECT PID be accessed?

Yes

Go to next step.

No

Go to Step 11.

F–224

TROUBLESHOOTING 

End Of Sie

9

Are DTCs present for two or more sensors 
connected to PCM terminal 2H?
Sensor connected to PCM terminal 2H:

• IAT sensor (P0112, P0113)

• FHO2S (P0131, P0132)

• RHO2S (P0138)

• Barometric pressure sensor (P2228, P2229)

• Manifold absolute pressure sensor (P0107, 

P0108)

• ECT sensor (P0117, P0118)

• TP sensor (P0122, P0123)

• TR switch (P0707, P0708)

• TFT sensor (P0712, P0713)

Yes

Go to next step.

No

Repair open GND circuit to sensor where constant 
voltage circuit inspection failed.

10

Turn ignition switch off.
Disconnect WDS or equivalent from DLC-2.
Disconnect PCM connector.
Measure resistance between GND circuit at 
appropriate sensor connector and PCM 
connector terminal 2H.
Is resistance less than 5.0 ohms?

Yes

Reconnect sensor connector.
Go to appropriate DTC test.

No

Repair open GND circuit.

11

Turn ignition switch off.
Disconnect PCM connector.
Measure resistance between battery negative 
terminal and PCM terminals 4X, 2AB, and 2AC.
Is each resistance less than 5.0 ohms?

Yes

Go to next step.

No

Repair open GND circuit.

12

Turn ignition switch off.
Measure resistance between GND circuit at  
following sensor connector and GND:

• IAT sensor (integated in MAF sensor)

• FHO2S

• RHO2S

• Barometric pressure sensor

• Manifold absolute pressure sensor

• ECT sensor

• TP sensor

• TR switch

• TFT sensor

Yes

GND circuits are okay.
Inspect for constant voltage at suspect sensor 
connector again.

No

Inspect for open GND circuit.

13

Turn ignition switch off.
Disconnect TP sensor and PCM connectors.
Turn ignition switch to ON position.
Measure voltage between constant voltage 
circuit at TP sensor connector and battery 
negative terminal.
Is voltage less than 0.5 V?

Yes

Inspect for constant voltage at suspect sensor 
connector again.

No

Repair constant voltage circuit shorted to power in 
harness.

14

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–225

F

NO.28 SPARK PLUG CONDITION

A6E398018881W30

Diagnostic procedure

28

SPARK PLUG CONDITION

DESCRIPTION

Incorrect spark plug condition

POSSIBLE CAUSE

Note

• Inspecting spark plugs condition can determine whether problem is related to a specific cylinder 

possibly all cylinders.

Wet/carbon stuck on specific plug:

• Spark—Weak, not visible

• Air/fuel mixture—Excessive fuel injection volume

• Compression—No compression, low compression

• Faulty spark plug

Grayish white with specific plug:

• Air/fuel mixture—Insufficient fuel injection volume

• Faulty spark plug

Wet/carbon is stuck on all plugs:

• Spark—Spark weak

• Air/fuel mixture—Too rich

• Compression—Low compression

• Clogging in intake/exhaust system

Grayish white with all plugs:

• Air/fuel mixture—Too lean

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

Remove all spark plugs.
Inspect spark plug condition.
Is spark plug condition okay?

Yes

Troubleshooting completed.

No

Specific plug is wet or covered with carbon:
Go to next step.
Specific plug looks grayish white:
Go to Step 7.
All plugs are wet or covered with carbon:
Go to Step 9.
All plugs look grayish white:
Go to Step 15.

2

Is spark plug wet/covered with carbon by engine 
oil?

Yes

Working up and down inspect all areas related to oil.

No

Go to next step.

3

Inspect spark plug for following:

• Cracked insulator

• Heat range

• Air gap

• Worn electrode

Is spark plug okay?

Yes

Go to next step.

No

Replace spark plug.

4

Inspect compression pressure at suspected 
faulty cylinder.
Is compression pressure correct?
(See 

B–9 COMPRESSION INSPECTION

.)

Yes

Go to next step.

No

Repair or replace malfunctioning parts.

5

Install all spark plugs.
Carry out spark test at suspected faulty cylinder.
Is strong blue spark visible? 
(Compare with normal cylinder.)

Yes

Go to next step.

No

Repair or replace malfunctioning parts.