Mazda 6. Manual - part 174

F–218

TROUBLESHOOTING 

End Of Sie

NO.20 FUEL ODOR (IN ENGINE COMPARTMENT)

A6E398018881W22

Diagnostic procedure

6

Install fuel pressure gauge between fuel pipe 
and fuel distributor.
Start engine and run it at idle.
Measure fuel line pressure 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.

7

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

Yes

Inspect spark plugs and CMP sensor.

No

Inspect following:

• High-tension leads

• Ignition coil and connector

8

Verify test results.

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

• If malfunction remains, replace PCM.

STEP

INSPECTION

RESULTS

ACTION

20

FUEL ODOR (IN ENGINE COMPARTMENT)

DESCRIPTION

Gasoline fuel smell or visible leakage

POSSIBLE CAUSE

• Excessive fuel pressure

• Purge solenoid valve malfunction

• Fuel tank vent system blockage

• Charcoal canister malfunction

• Fuel leakage from fuel system

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

Visually inspect for fuel leakage at fuel injector 
O-ring and fuel line.
Service as necessary.
Install fuel pressure gauge between fuel pipe 
and fuel distributor.
Start engine and run it at idle.
Measure fuel line pressure at idle.
Is fuel line pressure correct at idle?
(See 

F–20 FUEL LINE PRESSURE 

INSPECTION

)

Yes

Go to next step.

No

Replace fuel pump unit.

2

Inspect for blockage/restriction or open between 
engine vacuum port and charcoal canister.
Inspect for blockage in fuel tank vent system.
Is fault indicated?

Yes

Replace vacuum hose.

No

Go to next step.

3

Inspect purge solenoid valve.
(See 

F–39 PURGE SOLENOID VALVE 

INSPECTION

.)

Is solenoid operating properly?

Yes

Go to next step.

No

Replace purge solenoid valve.

TROUBLESHOOTING 

F–219

F

End Of Sie

NO.21 ENGINE NOISE

A6E398018881W23

Diagnostic procedure

End Of Sie

4

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 charcoal canister for fuel saturation.
If excess amount of liquid fuel is present, replace 
charcoal canister.

5

Verify test results.

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

• If malfunction remains, replace PCM.

STEP

INSPECTION

RESULTS

ACTION

21

ENGINE NOISE

DESCRIPTION

Engine noise from under hood

POSSIBLE CAUSE

Squeal, click or chirp noise:

• Improper engine oil level

• Improper drive belt tension

Rattle sound noise:

• Loose parts

Hiss sound noise:

• Vacuum leakage

• Loose spark plug

• Air leakage from intake-air system

• Improper variable air duct (VAD) control system operation

Rumble or grind noise:

• Improper drive belt tension

Rap or roar sound noise:

• Exhaust system looseness

Other noise:

• Camshaft friction gear noise or MLA noise

• Timing chain noise

STEP

INSPECTION

RESULTS

ACTION

1

Is squeal, click or chirp sound present?

Yes

Inspect engine oil level or drive belts.

No

Go to next step.

2

Is rumble or grind sound present?

Yes

Inspect drive belts.

No

Go to next step.

3

Is rattle sound present?

Yes

Inspect location of rattle for loose parts.

No

Go to next step.

4

Is hiss sound present?

Yes

Inspect for following:

• Vacuum leakage

• Spark plug looseness

• Intake-air system leakage

• Variable air duct (VAD) control system operation

(See 

F–238 Variable Air Duct (VAD) Control System 

Operation Inspection (L3 Engine Models)

.)

No

Go to next step.

5

Is rap or roar sound present?

Yes

Inspect exhaust system for loose parts.

No

Go to next step.

6

Is knock sound present?

Yes

Go to symptom troubleshooting "No.11 Knocking/
pinging".

No

If noise comes from engine internal, inspect for friction 
gear, timing chain or MLA noise.

7

Verify test results.

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

• If malfunction remains, replace PCM.

F–220

TROUBLESHOOTING 

NO.22 VIBRATION CONCERNS (ENGINE)

A6E398018881W24

Diagnostic procedure

End Of Sie

NO.23 A/C DOES NOT WORK SUFFICIENTLY

A6E398018881W25

Diagnostic procedure

22

VIBRATION CONCERNS (ENGINE)

DESCRIPTION

• Vibration from under hood or driveline

POSSIBLE CAUSE

• Loose attaching bolts or worn parts

• Components malfunction such as worn parts

STEP

INSPECTION

RESULTS

ACTION

1

Inspect following components for loose attaching 
bolts or worn parts:

• Cooling fan

• Condenser fan

• Drive belt and pulleys

• Engine mounts

All items okay?

Yes

Inspect following systems:

• Wheels

• ATX

• Driveline

• Suspension

No

Readjust or retighten engine mount installation 
position.
Service if necessary for other parts.

2

Verify test results.

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

• If malfunction remains, replace PCM.

23

A/C DOES NOT WORK SUFFICIENTLY.

DESCRIPTION

A/C compressor magnetic clutch does not engage when A/C switch is turned on.

POSSIBLE CAUSE

• Improper refrigerant charging amount

• Open A/C magnetic clutch

• Open circuit between A/C relay and A/C magnetic clutch

• Poor GND of A/C magnetic clutch

• Refrigerant pressure switch is stuck open.

• A/C relay is stuck open.

• Seized A/C compressor

• Open circuit between A/C switch and PCM through both refrigerant pressure switch and A/C amplifier

STEP

INSPECTION

RESULTS

ACTION

1

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.

2

Disconnect A/C compressor connector.
Start engine and turn A/C switch on.
Is there correct voltage at terminal of A/C 
compressor magnetic clutch connector?

Specification

More than 10.5 V

Yes

Inspect for GND condition of magnetic clutch on A/C 
compressor.
If GND condition is okay, inspect for open circuit 
magnetic clutch coil.

No

Go to next step.

3

Disconnect refrigerant pressure switch 
connector.
Connect jumper wire between terminals of A/C 
high pressure switch connector.
Connect jumper wires between terminals of 
refrigerant pressure switch connector.
Connect WDS or equivalent to DLC-2.
Access ACSW PID.
Turn ignition switch to ON position.
Turn A/C switch on and set blower fan at any 
speed.
Does ACSW PID read ON?

Yes

Inspect refrigerant pressure switch operation.
If switch is okay, go to next step.

No

Inspect for following:

• A/C switch is stuck open.

• Open circuit between refrigerant pressure switch 

and PCM terminal 1AC

• Open circuit of blower motor fan switch and resistor 

(if blower motor does not operate)

• Evaporator temperature sensor and A/C amplifier

4

Remove jumper wire from switch connector.
Reconnect connector to refrigerant pressure 
switch.
Start engine and turn A/C switch on.
Does fan operate?

Yes

Inspect for stuck open A/C relay.
Replace if necessary.

No

Inspect following and repair or replace as necessary:

• Refrigerant charging amount

• A/C compressor for being seized

5

Verify test results.

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

• If malfunction remains, replace PCM.

TROUBLESHOOTING 

F–221

F

End Of Sie

NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY

A6E398018881W26

Diagnostic procedure

End Of Sie

NO.25 A/C IS NOT CUT OFF UNDER WIDE OPEN THROTTLE CONDITIONS

A6E398018881W27

Diagnostic procedure

24

A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY.

DESCRIPTION

A/C compressor magnetic clutch does not disengage.

POSSIBLE CAUSE

• Stuck engagement A/C compressor magnetic clutch

• A/C relay is stuck closed.

• Short to GND between A/C switch and PCM

• Short to GND circuit between A/C relay and PCM

• A/C relay to magnetic clutch circuit shorted to battery power

STEP

INSPECTION

RESULTS

ACTION

1

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.

2

Start engine and run it at idle.
Turn A/C switch on.
Remove A/C relay.
Does A/C magnetic clutch disengage?

Yes

Inspect for following:

• A/C relay is stuck closed.

• Short to GND circuit between A/C relay and PCM 

terminal 4O.

If both items okay, go to next step.

No

Inspect if circuit between A/C relay and magnetic 
clutch shorts to battery power circuit.
If circuit is okay, inspect magnetic clutch stuck 
engagement or clearance.

3

Connect WDS or equivalent to DLC-2.
Access ACSW PID.
Start engine and turn A/C switch on.
Read ACSW PID while disconnecting refrigerant 
pressure switch connector.

Note

• ACSW PID should read OFF when 

disconnecting connector. If ACSW PID 
reading remains ON, short to GND circuit 
may be present.

Does ACSW PID reading remain ON?

Yes

Inspect for short to GND circuit between refrigerant 
pressure switch and PCM terminal 1AC.

No

Go to next step.

4

Reconnect refrigerant pressure switch 
connector.
Read ACSW PID while turning off A/C switch.

Note

• ACSW PID should read OFF when turning 

A/C switch off. If ACSW PID reading 
remains ON, short to GND circuit may be 
present.

Does ACSW PID reading remain ON?

Yes

Inspect following:

• Short to GND circuit between A/C switch and A/C 

amplifier

• Short to GND circuit between A/C amplifier and 

refrigerant pressure switch

No

Inspect for stuck closed A/C switch.

5

Verify test results.

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

• If malfunction remains, replace PCM.

25

A/C IS NOT CUT OFF UNDER WOT CONDITIONS.

DESCRIPTION

A/C compressor magnetic clutch does not disengage under WOT.

POSSIBLE CAUSE

• TP sensor malfunction

• TP sensor misadjustment

• Loosely installed TP sensor.

STEP

INSPECTION

RESULTS

ACTION

1

Does A/C compressor disengage when A/C 
switch is turned off?

Yes

Go to next step.

No

Go to symptom troubleshooting "No.24 A/C is always 
on or A/C compressor runs continuously".