2002 MAZDA 6 engine overheat

F2–184
TROUBLESHOOTING
NO.7 SLOW RETURN TO IDLEA6E408018881209
Diagnostic Procedure
7 SLOW RETURN TO IDLE
DESCRIPTION•Engine takes more time than normal to return to idle speed.
•Engine speed continues at fast idle after warm-up.
POSSIBLE
CAUSE•Thermostat is stuck open
•Fuel injection timing is incorrect
•Erratic signal from CKP sensor
•Erratic signal from CMP sensor
•ECT sensor or related circuit malfunction
•Accelerator position sensor or related circuit malfunction
•Idle switch or related circuit malfunction
•MAF/IAT sensor or related circuit malfunction
•Fuel pressure sensor or related circuit malfunction
•Incorrect adjustment accelerator pedal position sensor and/or idle switch
•Incorrect idle speed
•Excessive fuel pressure
•Supply pump malfunction
•Suction control valve malfunction (built-in supply pump)
•Fuel pressure limiter malfunction (built-in common rail)
•Fuel injector malfunction (incorrect fuel regulate pressure)
•Neutral switch or related circuit 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 Connect WDS or equivalent to DLC-2.
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.
2 Access ECT PID.
Start and warm-up engine to normal operating
temperature.
Is ECT PID reading between 82—112 °C {180—
233 °F}?Yes Go to next step.
NoECT PID is higher than 112 °C {233 °F}:
Go to symptom troubleshooting “NO.17 COOLING
SYSTEM CONCERNS-OVERHEATING”.
ECT PID is less than 82 °C {180 °F}:
Go to symptom troubleshooting “NO.18 COOLING
SYSTEM CONCERNS-RUNS COLD”.

F2–186
TROUBLESHOOTING
NO.8 ENGINE RUNS ROUGH/ROLLING IDLEA6E408018881210
Diagnostic Procedure
8 ENGINE RUNS ROUGH/ROLLING IDLE
DESCRIPTION•Engine speed fluctuates between specified idle speed and lower speed and engine shakes excessively.
•Idle speed is too slow and engine shakes excessively.
POSSIBLE
CAUSE•Poor fuel quality
•Air leakage from intake-air system
•Intake-air system restriction
•Incorrect idle speed
•Engine overheating
•Cooling fan No.1 system malfunction
•A/C system improper operation
•EGR system improper operation
•EGR water cooler malfunction
•Fuel leakage
•Inadequate fuel pressure
•Fuel pressure sensor or related circuit malfunction
•Suction control valve malfunction (built-in supply pump)
•Fuel pressure limiter malfunction (built-in common rail)
•Fuel filter clogging
•Fuel line restriction
•Incorrect fuel injection timing
•Erratic signal from CKP sensor
•Erratic signal from CMP sensor
•ECT sensor or related circuit malfunction
•Idle switch misadjustment
•Idle switch or related circuit malfunction
•Accelerator position sensor misadjustment
•Accelerator position sensor or related circuit malfunction
•MAF/IAT sensor malfunction
•Neutral switch or related circuit malfunction
•Supply pump malfunction
•Fuel injector malfunction
•Low engine compression
•Improper valve timing
•Engine compression excessive unbalance for each cylinder
•Unbalanced fuel injection amount for each cylinder
•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 Inspect for following:
•Fuel quality (e.g.: including water
contamination, winter/summer blend)
•Fuel line/fuel filter clogging
•Loose bands on intake-air system
•Cracks on intake-air system parts
•Intake-air system restriction
•Vacuum leakage
•Cooling fan No.1 system operation
Are all items okay?Yes Go to next step.
No Service as necessary
Repeat Step 1.
2 Is engine overheating? Yes Go to symptom troubleshooting “NO.17 COOLING
SYSTEM CONCERNS—OVERHEATING.”
No Go to next step.

TROUBLESHOOTING
F2–189
F2
NO.9 FAST IDLE/RUNS ONA6E408018881211
Diagnostic Procedure
End Of Sie
9 RUNS IDLE/RUNS ON
DESCRIPTION•Engine speed continues at fast idle after warm-up.
•Engine runs after engine key turned off.
POSSIBLE
CAUSE•ECT sensor or related circuit malfunction
•Incorrect adjustment accelerator position sensor and/or idle switch
•Suction control valve (built-in supply pump)
•Fuel injector malfunction
•IDM or related circuit malfunction
•Vacuum leakage
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 Connect WDS or equivalent to DLC-2.
Access ECT PID.
Start and warm-up engine to normal operating
temperature.
Is ECT PID reading between 82—112 °C {180—
233 °F}?Yes Go to next step.
NoECT PID is higher than 112 °C{233 °F}:
Go to symptom troubleshooting “NO.17 COOLING
SYSTEM CONCERNS—OVERHEATING”.
ECT PID is less than 82 °C{180 °F}:
Go to symptom troubleshooting “NO.18 COOLING
SYSTEM CONCERNS—RUNS COLD”.
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.
3 Inspect suction control valve.
(See F2–54 SUCTION CONTROL VALVE
INSPECTION)
Is suction control valve okay?Yes Go to next step.
No Repair supply pump.
(See F2–54 SUPPLY PUMP INSPECTION)
4 Inspect fuel injector.
(See F2–56 FUEL INJECTOR INSPECTION)
Is fuel injector okay?Yes Go to next step.
No Replace fuel injector.
(See F2–55 FUEL INJECTOR REMOVAL/
INSTALLATION)
5 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 Inspect vacuum leakage.
No Adjust accelerator position sensor and idle switch
correctly.
(See F2–73 ACCELERATOR POSITION SENSOR
ADJUSTMENT)
(See F2–71 IDLE SWITCH ADJUSTMENT)
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)

F2–192
TROUBLESHOOTING
End Of Sie
NO.11 ENGINE STALLS/QUITS, ENGINE RUNS ROUGH, MISSES, BUCK/JERK, HESITATION/STUMBLE,
SURGES
A6E408018881213
17 Inspect IDM.
(See F2–84 INJECTOR DRIVER MODULE
(IDM) INSPECTION)
Is IDM okay?Yes Remove and inspect supply pump and common rail.
No Repair or replace as necessary.
18 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
11ENGINE STALLS/QUITS, ENGINE RUNS ROUGH, MISSES, BUCK/JERK, HESITATION/STUMBLE,
SURGES
DESCRIPTION•Engine stops unexpectedly at beginning of acceleration or during cruise.
•Engine stops unexpectedly while cruising.
•Engine speed fluctuates during acceleration or cruising.
•Engine misses during acceleration or cruising.
•Vehicle bucks/jerks during acceleration, during or deceleration.
•Momentary pause at beginning of acceleration or during acceleration.
•Momentary minor irregularity in engine output.
POSSIBLE
CAUSE•Poor fuel quality
•Glow system malfunction
•Air leakage from intake-air system
•Intake-air system restriction or clogging
•Engine overheating
•A/C system improper operation
•Turbocharger malfunction
•Variable swirl control (VSC) system malfunction
•EGR system malfunction
•Neutral switch or related circuit malfunction
•Cooling fan No.1 or cooling fan No.2 seat are improper
•Fuel line clogging or restriction
•Fuel filter clogging or restriction
•Incorrect fuel injection timing
•Erratic signal from CKP sensor
•Erratic signal from CMP sensor
•ECT sensor or related circuit malfunction
•Boost sensor or related circuit malfunction
•Accelerator position sensor or related circuit malfunction
•Idle switch or related circuit malfunction
•MAF/IAT sensor or related circuit malfunction
•IAT sensor No.2 or related circuit malfunction
•VSS or related circuit malfunction
•Incorrect adjustment accelerator position sensor and/or idle switch
•Incorrect idle speed
•Inadequate fuel pressure
•Fuel pressure sensor or related circuit malfunction
•Suction control valve malfunction (built-in supply pump)
•Fuel pressure limiter malfunction (built-in common rail)
•Supply pump malfunction
•Fuel injector malfunction
•Low engine compression
•Improper valve timing
•Exhaust system and/or catalyst converter restriction
•Clutch slippage
•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.

TROUBLESHOOTING
F2–193
F2
Diagnostic Procedure
STEP INSPECTION RESULTS ACTION
1 Is idle speed stable? Yes Go to next step.
No Go to symptom troubleshooting “NO.8 ENGINE RUNS
ROUGH/ROLLING IDLE”.
2 Is engine overheating? Yes Go to symptom troubleshooting “NO.17 COOLING
SYSTEM CONCERNS—OVERHEATING”.
No Go to next step.
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.
4 Inspect for following:
•Fuel quality (e.g.: including water
contamination, winter/summer blend)
•Fuel line/fuel filter clogging and/or restriction
•Intake-air system restriction or clogging
•Exhaust system and/or catalyst converter
restriction
•Cooling fan No.1 or cooling fan No.2 seat
Are all items okay?Yes Go to next step.
No Service as necessary.
Repeat Step 4.
5 Does engine run normal after warm-up? Yes Inspect glow system operation.
(See T–19 RELAY INSPECTION)
Replace any malfunctioning part as necessary.
If glow system is okay, go to next step.
No Go to next step.
6Note
•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 CONTINUITY”.
Other symptoms:
Inspect following:
•Refrigerant charging amount
•Cooling fan No.1 and/or cooling fan No.2 operation
7 Inspect hose bands between following parts:
•Turbocharger compressor housing and air
cleaner
•Turbocharger compressor housing and
charge air cooler
Are hose bands loose?Yes Retighten hose bands.
If concern is resolved, complete inspection.
If concern still exists, go to next step.
No Go to next step.
8 Inspect for improper operation, kinks, clogging or
disconnection on guide blade actuator.
Is guide blade actuator okay?Yes Turbocharger is okay.
Go to next step.
No Repair or replace as necessary.
If concern is resolved, complete inspection.
If concern still exists, turbocharger is okay.
Go to next step.
9 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.
10 Inspect idle speed.
(See F2–34 IDLE SPEED INSPECTION)
Is idle speed correct?Yes Go to next step.
No Repair or replace malfunctioning part according to idle
speed inspection results.

TROUBLESHOOTING
F2–195
F2
NO.12 LACK/LOSS OF POWER-ACCELERATION/CRUISEA6E408018881214
Diagnostic Procedure
12 LACK/LOSS OF POWER-ACCELERATION CRUISE
DESCRIPTION•Performance is poor under load (e.g., power down when climbing hills).
POSSIBLE
CAUSE•Poor fuel quality
•Air leakage from intake-air system
•Intake-air system restriction or clogging
•Engine overheating
•A/C system improper operation
•Improper operation of A/C cut-off control
•Variable boost control (VBC) system malfunction
•Variable swirl control (VSC) system malfunction
•EGR system malfunction
•Vacuum leakage
•Clutch slippage
•Exhaust system and/or catalyst converter restriction
•Fuel line or clogging or restriction
•Fuel filter clogging or restriction
•Incorrect fuel injection timing
•Erratic signal from CKP sensor
•Erratic signal from CMP sensor
•ECT sensor or related circuit malfunction
•Boost sensor or related circuit malfunction
•Accelerator position sensor or related circuit malfunction
•Idle switch or related circuit malfunction
•MAF/IAT sensor or related circuit malfunction
•IAT sensor No.2 or related circuit malfunction
•Incorrect adjustment accelerator position sensor and/or idle switch
•Incorrect idle speed
•Inadequate fuel pressure
•Fuel pressure sensor or related circuit malfunction
•Suction control valve malfunction (built-in supply pump)
•Fuel pressure limiter malfunction (built-in common rail)
•Supply pump malfunction
•Fuel injector malfunction
•Low engine compression
•Improper valve timing
•Cooling fan No.1 or cooling fan No.2 seat are improper
•Turbocharger malfunction
•Charge air cooler malfunction
•Brake system dragging
•Intake shutter valve malfunction
•Guide blade valve 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 idle speed stable? Yes Go to next step.
No Go to symptom troubleshooting “NO.8 ENGINE RUNS
ROUGH/ROLLING IDLE”.
2 Is engine overheating? Yes Go to symptom troubleshooting “NO.17 COOLING
SYSTEM CONCERNS—OVERHEATING”.
No Go to next step.

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.