2002 MAZDA 6 cooling

TROUBLESHOOTING
F2–199
F2
NO.13 KNOCKING/PINGINGA6E408018881215
Diagnostic Procedure
13 KNOCKING/PINGING
DESCRIPTION•Excessive shrilly knocking sound from engine.
POSSIBLE
CAUSE•Poor fuel quality
•Air leakage from intake-air system
•Intake-air system restriction or clogging
•Variable swirl control (VSC) system malfunction
•Variable boost control (VBC) system malfunction
•Intake shutter valve stuck close
•VSC valve stuck close
•Glow system malfunction
•Low engine compression
•Improper valve timing
•Low coolant temperature
•Incorrect fuel injection timing
•Erratic signal from CKP sensor
•Erratic signal from CMP sensor
•ECT sensor or related circuit malfunction
•MAF/IAT sensor or related circuit malfunction
•IAT sensor No.2 or related circuit malfunction
•Boost sensor or related malfunction
•Fuel pressure sensor or related circuit malfunction
•Accelerator position sensor or related circuit malfunction
•Excessive fuel pressure
•Fuel return line clogging or restriction
•EGR system malfunction
•Exhaust system and/or catalyst converter restriction
•Turbocharger malfunction
•Charge air cooler malfunction
•Suction control valve malfunction (built-in supply pump)
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 injury 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.
STEP INSPECTION RESULTS ACTION
1 Does engine run cold? Yes Go to symptom troubleshooting “NO.18 COOLING
SYSTEM CONCERNS—RUNS COLD”.
No Go to next step.
2 Inspect for following:
•Fuel quality (e.g.: including water
contamination, winter/summer blend)
•Fuel return line clogging and/or restriction
•Intake-air system restriction or clogging
•Exhaust system and/or catalyst converter
restriction or clogging
•Charge air cooler condition (restriction or
damaged)
Are all items okay?Yes Go to next step.
No Service as necessary.
Repeat Step 2.
3 Connect WDS or equivalent to DLC-2.
Access ECT PID.
Verify ECT PID is above 80 °C {176 °F}?Yes Go to next step.
No Inspect ECT PID.

F2–202
TROUBLESHOOTING
NO.14 POOR FUEL ECONOMYA6E408018881216
Diagnostic Procedure
14 POOR FUEL ECONOMY
DESCRIPTION•Fuel economy is unsatisfactory.
POSSIBLE
CAUSE•Incorrect idle speed
•A/C system improper operation
•Intake -air system clogging or restriction
•Engine cooling system malfunction
•Poor fuel quality
•Improper coolant level
•Erratic signal from CKP sensor
•Erratic signal from CMP sensor
•Fuel pressure sensor or related circuit malfunction
•ECT sensor or related circuit malfunction
•Boost sensor or related circuit malfunction
•Accelerator position sensor or related circuit malfunction
•Incorrect adjustment idle switch
•MAF/IAT sensor or related circuit malfunction
•IAT sensor No .2 or related circuit malfunction
•VSS or related circuit malfunction
•Turbocharger malfunction
•Charge air cooler malfunction
•Low engine compression
•Improper valve timing
•Exhaust system and/or catalyst converter clogging
•Incorrect fuel injection timing
•Fuel injector malfunction
•Supply pump malfunction
•Fuel leakage
•Fuel line clogging or restriction
•Fuel filter clogging or restriction
•Brake dragging
•EGR system malfunction
•Vacuum leakage
•Clutch slippage
•Variable boost control (VBC) system malfunction
•Coolant heater system 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 injury 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.
STEP INSPECTION RESULTS ACTION
1 Inspect for following:
•Fuel quality (e.g.: including water
contamination, winter/summer blend)
•Fuel line/fuel filter clogging and/or restriction
•Fuel line leakage
•Intake-air system restriction
•Exhaust system and/or catalyst converter
restriction
•Charge air cooler condition (restriction or
damaged)
•Vacuum leakage
Are all items okay?Yes Go to next step.
No Service as necessary.
Repeat Step 1.
2 Is brake system functioning properly? Yes Go to next step.
No Inspect for cause.

TROUBLESHOOTING
F2–203
F2
3 Perform self-test function using WDS or
equivalent.
Turn engine switch to ON.
Retrieve any DTC.
Is DTC displayed?YesDTC is displayed:
Go to appropriate DTC test.
Communication error message is displayed:
Inspect for following:
•Open circuit between PCM control relay and PCM
terminal 53 or 79
•Open circuit PCM control relay and PCM terminal
69
•PCM control relay stuck open
•Open or poor GND circuit (PCM terminal 65, 85,
103 or 104)
•Poor connection vehicle body GND
NoNo DTC is displayed:
Go to next step.
4Note
•The following test should be performed on
the vehicles with A/C system. If the
following test cannot be performed due to
engine stalling, go to next step.
•Go to next step for the vehicle without A/C
system.
Connect pressure gauge to A/C line.
Turn blower and A/C switches on.
Is pressure within specifications?Yes Go to next step
NoA/C is always on:
Go to symptom troubleshooting “NO.24 A/C ALWAYS
ON OR A/C COMPRESSOR RUNS
CONTINUOUSLY”.
Other symptoms:
Inspect following:
•Refrigerant charging amount
•Cooling fan No.1 and/or cooling fan No.2
operation.
5 Access ECT PID.
Drive vehicle while monitoring PID.
Is PID within specification?Yes Go to next step.
No Inspect for coolant leakage, cooling fan No.1 and
cooling fan No.2 operations or thermostat operation.
6 Inspect idle speed.
(See F2–34 IDLE SPEED INSPECTION)
Is idle speed okay?Yes Go to next step.
No Go to symptom troubleshooting “NO.7 SLOW
RETURN TO IDLE”.
7 Perform EGR system inspection.
Is EGR system okay?Yes Go to next step.
No Repair or replace malfunctioning part according to
EGR system operation results.
8 Inspect adjustment of accelerator position
sensor and idle switch.
(See F2–72 ACCELERATOR POSITION
SENSOR INSPECTION)
(See F2–70 IDLE SWITCH INSPECTION)
Are accelerator position sensor and idle switch
adjusted correctly?Yes Go to next step.
No Adjust accelerator position sensor and idle switch
correctly.
(See F2–73 ACCELERATOR POSITION SENSOR
ADJUSTMENT)
(See F2–71 IDLE SWITCH ADJUSTMENT)
9 Is engine compression correct?
(See B2–8 COMPRESSION INSPECTION)Yes Go to next step.
No Inspect for following:
•Damaged valve seat
•Worn valve stem and valve guide
•Worn or stuck piston ring
•Worn piston, piston ring or cylinder
•Improper valve timing
Service as necessary.
10 Inspect fuel injector.
(See F2–56 FUEL INJECTOR INSPECTION)
Is fuel injector okay?Yes Go to next step.
No Repair or replace as necessary.
11 Perform turbocharger inspection.
(See F2–38 TURBOCHARGER INSPECTION)
Is turbocharger okay?Yes Go to next step.
No Replace turbocharger.
12 Inspect guide blade valve operation.
(See F2–229 ENGINE CONTROL SYSTEM
OPERATION INSPECTION)
Is there any problem?Yes Repair or replace as necessary.
No Go to next step.
13 Visually inspect CKP sensor and teeth of pulse
wheel.
Are CKP sensor and teeth of pulse wheel okay?Yes Go to next step.
No Replace malfunctioning parts. STEP INSPECTION RESULTS ACTION

TROUBLESHOOTING
F2–205
F2
NO.15 EMISSION COMPLIANCEA6E408018881217
Diagnostic Procedure
15 EMISSION COMPLIANCE
DESCRIPTION•Fails emissions test.
POSSIBLE
CAUSE•Poor fuel quality
•Vacuum leakage
•Air leakage from intake-air system
•Intake-air system restriction or clogging
•Variable swirl control (VSC) system malfunction
•Variable boost control (VBC) system malfunction
•Intake shutter valve stuck close
•VSC valve stuck close
•Turbocharger malfunction
•Guide blade valve malfunction
•Charge air cooler malfunction
•Glow system malfunction
•EGR system malfunction
•EGR water cooler malfunction
•Low coolant temperature
•Engine overheating
•Inadequate fuel pressure
•Fuel pressure limiter malfunction (built-in common rail)
•Suction control valve inspection (built-in supply pump)
•ECT sensor or related circuit malfunction
•MAF/IAT sensor related circuit malfunction
•IAT sensor No.2 or related circuit malfunction
•Fuel pressure sensor or related circuit malfunction
•Incorrect adjustment accelerator position sensor and/or idle switch
•Accelerator position sensor or related circuit malfunction
•Idle switch or related circuit malfunction
•Fuel line rclogging or restriction
•Supply pump malfunction
•Fuel injector malfunction
•Incorrect fuel injection timing
•Incorrect idle speed
•Erratic signal from CKP sensor
•Erratic signal from CMP sensor
•Boost sensor or related circuit malfunction
•Neutral switch or related circuit malfunction
•VSS or related circuit malfunction
•Low engine compression
•Improper valve timing
•Base engine malfunction
•Exhaust system and/or catalyst converter restriction
•Catalyst converter malfunction
•IDM or related circuit 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 injury 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.
STEP INSPECTION RESULTS ACTION
1 Is engine overheating? Yes Go to symptom troubleshooting “NO.17 COOLING
SYSTEM CONCERNS—OVERHEATING”.
No Go to next step.
2 Does engine run cold? Yes Go to symptom troubleshooting “NO.18 COOLING
SYSTEM CONCERNS—RUNS COLD”.
No Go to next step.

F2–210
TROUBLESHOOTING
End Of SieNO.17 COOLING SYSTEM CONCERNS-OVERHEATINGA6E408018881219
Diagnostic Procedure
17
COOLING SYSTEM CONCERNS-OVERHEATING
DESCRIPTION•Engine runs at higher than normal temperature/overheats.
POSSIBLE
CAUSE•Cooling fan No.2 malfunction
•Cooling fan No.1 malfunction
•Low drive belt tension
•Drive belt damage
•Improper coolant level
•Thermostat malfunction
•Radiator clogging
•Improper water/anti-freeze mixture
•Improper or damaged radiator cap
•Radiator hose damage
•Coolant leakage (engine internal, turbocharger, external)
•A/C system malfunction
•EGR system malfunction
•Coolant heater system malfunction
STEP INSPECTION RESULTS ACTION
1 Inspect following:
•Engine coolant level
•Coolant leakage (around heater unit in
passenger compartment, coolant hoses and/
or radiator, and around coolant heater unit.)
•Water and anti-freeze mixture
•Radiator condition
•Collapsed or restricted radiator hoses
•Radiator pressure cap
•Drive belt tension
•Drive belt
•Fan rotational direction
Are all items okay?Yes Go to next step.
No Service as necessary.
Repeat Step 1.
2 Perform self-test function using WDS or
equivalent.
Turn engine switch to ON.
Retrieve any DTC.
Is DTC displayed?YesDTC is displayed:
Go to appropriate DTC test.
Communication error message is displayed:
Inspect for following:
•Open circuit between PCM control relay and PCM
terminal 53 or 79
•Open circuit PCM control relay and PCM terminal
69
•PCM control relay stuck open
•Open or poor GND circuit (PCM terminal 65, 85,
103 or 104)
•Poor connection vehicle body GND
NoNo DTC is displayed:
Go to next step.

TROUBLESHOOTING
F2–211
F2
End Of Sie
3Note
•The following test should be performed on
the vehicles with A/C system. Go to next
step for vehicles without A/C system
Start engine and run it at idle speed.
Turn A/C switch off.
Does A/C compressor disengaged?Yes Go to next step.
No Go to symptom troubleshooting “NO.24 A/C ALWAYS
ON OR A/C COMPRESSOR RUNS
CONTINUOUSLY”.
4 Start engine and run it at idle speed.
Turn A/C switch on if equipped.
Do cooling fan No.1 and/or cooling fan No.2
operate?Yes Go to next step.
NoCooling fan No.1 does not operate:
Inspect for following:
•Cooling fan relay No.1 is stuck open
•Cooling fan motor No.1 malfunction
•Cooling fan motor No.1 GND open
•Open circuit between cooling fan motor No.1 and
relay
•Open circuit between cooling fan relay No.1 and
PCM terminal 102
•Open battery power circuit of cooling fan relay
No.1
Cooling fan No.2 does not operate:
Inspect for following:
•Cooling fan relay No.2 is stuck open
•Cooling fan motor No.2 malfunction
•Cooling fan motor No.2 GND open
•Open circuit between Cooling fan motor No.2 and
relay
•Open circuit between Cooling fan relay No.2 and
PCM terminal 76
•Open battery power circuit of Cooling fan relay
No.2
5 Is drive belt okay? Yes Go to next step.
No Replace drive belt.
6 Perform EGR system inspection.
Is EGR system okay?Yes Go to next step.
No Repair or replace malfunctioning part according to
EGR system operation results.
7 Perform coolant heater system inspection.
(See E–10 THERMOSTAT INSPECTION)
Is coolant heater system okay?Yes Go to next step.
No Repair or replace malfunctioning part according to
coolant heater system operation results.
8 Cool down engine.
Remove thermostat and inspect operation.
Is thermostat okay?Yes Thermostat is okay.
Inspect cylinder block for leakage or blockage.
No Replace thermostat.
9 Verify test results.
•If okay, return to diagnostic index to service any additional symptoms.
•If malfunction remains, replace PCM. (See F2–64 PCM REMOVAL/INSTALLATION) STEP INSPECTION RESULTS ACTION

F2–212
TROUBLESHOOTING
NO.18 COOLING SYSTEM CONCERNS-RUNS COLDA6E408018881220
Diagnostic Procedure
End Of Sie
18 COOLING SYSTEM CONCERNS-RUNS COLD
DESCRIPTION•Engine takes excessive period for reaching normal operating temperature.
POSSIBLE
CAUSE•Thermostat malfunction
•Cooling fan No.2 system malfunction
•Cooling fan No.1 system malfunction
•Coolant heater system malfunction
STEP INSPECTION RESULTS ACTION
1 Is customer complaint “Lack of passenger
compartment heat”?Yes Inspect A/C heater system.
No Go to next step.
2 Does engine speed continue at fast idle? Yes Go to symptom troubleshooting “NO.7 SLOW
RETURN TO IDLE”.
No Go to next step.
3 Connect WDS or equivalent to DLC-2.
Access ECT PID.
Inspect for both ECT PID and temperature
gauge on instrument cluster readings.
Is ECT PID same as temperature gauge
reading?Yes Go to next step.
No If temperature gauge on instrument cluster indicates
normal range but ECT PID is not same as temperature
gauge reading, inspect ECT sensor.
If temperature gauge on instrument cluster indicates
cold range but ECT PID is normal, inspect
temperature gauge and heat gauge unit.
4 Remove thermostat and inspect operation.
(See E–9 THERMOSTAT REMOVAL/
INSTALLATION)
(See E–10 THERMOSTAT INSPECTION)
Is thermostat okay?Yes Go to next step.
No Replace thermostat.
5 Inspect cooling fan No.1 and cooling fan No.2
operations.
If both or either fan operate normally, inspect for
following:
•Cooling fan relay No.2 is stuck closed
•Short to GND between cooling fan relay No.2
and PCM terminal 76
•Circuit between cooling fan relay No.2 and
fan motor short to battery supply line
•Cooling fan relay No.1 is stuck closed
•Short to GND between cooling fan relay No.1
and PCM terminal 102
•Circuit between cooling fan relay No.1 and
fan motor short to battery supply line
•Short to GND between A/C switch and PCM
terminal 84
Are all circuits okay?Yes Perform coolant heater system inspection.
Repair or replace malfunctioning part according to
coolant heater system operation results.
No Repair or replace as necessary.
6 Verify test results.
•If okay, return to diagnostic index to service any additional symptoms.
•If malfunction remains, replace PCM. (See F2–64 PCM REMOVAL/INSTALLATION)

F2–220
TROUBLESHOOTING
NO.22 VIBRATION CONCERNS (ENGINE)A6E408018881224
Diagnostic Procedure
22 VIBRATION CONCERNS (ENGINE)
DESCRIPTION•Vibration from under hood or driveline.
POSSIBLE
CAUSE•Loose attaching bolts or worn parts
•Cooling fan No.1 or cooling fan No.2 seat are improper
•Engine or transaxle mounts are improperly installed
•Components malfunction such as worn parts
•Erratic signal from CMP sensor
•ECT sensor or related circuit malfunction
•Accelerator position sensor or related circuit malfunction
•MAF/IAT sensor or related circuit malfunction
•Idle switch or related circuit malfunction
•Incorrect adjustment of accelerator position sensor and/or idle switch
•Fuel injector malfunction
•Vacuum leakage
•Improper tension or damaged drive belts
•Improper balance of wheels or tires
•Driveline malfunction
•Suspension 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 injury 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.
STEP INSPECTION RESULTS ACTION
1 Inspect following components for loose attaching
bolts or worn parts:
•Cooling fan No.1
•Cooling fan No.2
•Cooling fan No.1 and cooling fan No.2 seat
•Drive belt and pulley
•Engine mounts
•Exhaust system
Are all items okay?Yes Go to next step.
No Readjust or retighten engine mount installation
position.
Service as necessary for other parts.
2 Inspect vacuum leakage.
Are vacuum hoses okay?Yes Go to next step.
No Service as necessary.
Repeat Step 2.