2002 MAZDA 6 compression ratio

F2–180
TROUBLESHOOTING
15 Is there any restriction in exhaust system or
catalyst converter?Yes Repair or replace as necessary.
No Go to next step.
16 Access RPM PID.
Is RPM PID indicating engine speed during
cranking engine?Yes Go to next step.
No Go to Step 19.
17Note
•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
18 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)
19 Depress accelerator pedal slightly.
Crank engine.
Does engine start now?Yes Inspect idle speed.
(See F2–34 IDLE SPEED INSPECTION)
No Go to next step.
20 Inspect for fuel leakage from fuel pipe.
Is any fuel leakage found on fuel pipe?Yes Repair or replace as necessary.
No Go to next step.
21 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.
22 Measure gap between CKP sensor and teeth of
pulse wheel.
Specification
1.5—2.5 mm {0.059—0.098 in}
Is gap within specification?Yes Go to next step.
No Adjust CKP sensor position.
23 Visually inspect CMP sensor and teeth of pulse
wheel.
Are CMP sensor and teeth of pulse wheel okay?Yes Inspect following PIDs:
(See F2–65 PCM INSPECTION)
•ECT
•IAT
•MAF
•RPM
If PID value is not as specified, repair or replace
malfunctioning parts.
If PID value is okay, go to next step.
No Replace malfunctioning parts.
24 Inspect fuel pressure sensor.
(See F2–79 FUEL PRESSURE SENSOR
INSPECTION)
Is fuel pressure okay?Yes Go to next step.
No Replace common rail.
25 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)
26 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.
27 Inspect fuel injector.
(See F2–56 FUEL INJECTOR INSPECTION)
Is fuel injector okay?Yes Go to next step.
No Repair or replace as necessary. STEP INSPECTION RESULTS ACTION

TROUBLESHOOTING
F2–181
F2
End Of Sie
NO.6 CRANKS NORMALLY BUT WILL NOT STARTA6E408018881208
Diagnostic Procedure
28 Inspect IDM.
(See F2–84 INJECTOR DRIVER MODULE
(IDM) INSPECTION)
Is IDM okay?Yes Go to next step.
No Repair or replace as necessary.
29 Inspect EGR system operation.
Is EGR system operation normal?Yes Remove and inspect supply pump and common rail.
No Repair or replace malfunctioning part according to
EGR system operation results.
30 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
6 CRANKS NORMALLY BUT WILL NOT START
DESCRIPTION•Starter cranks engine at normal speed but engine will not run.
•Refer to symptom troubleshooting “No.5 Engine stalls” if this symptom appears after engine stall.
•Fuel is in fuel tank.
•Battery is in normal condition.
POSSIBLE
CAUSE•Poor fuel quality
•Intake-air system restriction
•Fuel line restriction
•EGR system malfunction
•Glow system malfunction
•Fuel pressure sensor or related circuit malfunction
•Suction control valve malfunction (built-in supply pump)
•Fuel pressure limiter malfunction (built-in common rail)
•Fuel leakage
•Fuel filter clogging
•Incorrect fuel injection timing
•Erratic signal from CKP sensor
•Erratic signal from CMP sensor
•V-reference supply circuit malfunction
•ECT sensor or related circuit malfunction
•Supply pump malfunction
•Fuel injector malfunction
•Immobilizer system (PATS) and/or circuit malfunction (if equipped)
•Low engine compression
•Improper valve timing
•IDM or related circuit malfunction
•PCM control repay 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
1Note
•The following test should be perform 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.YesBoth conditions appear:
Go to Step 4.
NoEither or other condition appears:
Go to next step.
2 Is coil connector securely connected to coil? Yes Go to next step.
No Connect coil connector securely.
Return to Step 1.

TROUBLESHOOTING
F2–183
F2
End Of Sie
13 Inspect glow system operation.
(See T–19 RELAY INSPECTION)
Is glow system operation normal?Yes Go to next step.
No Repair or replace malfunctioning part according to
glow system operation results.
14 Inspect for fuel leakage from fuel pipe.
Is any fuel leakage found on fuel pipe?Yes Repair or replace as necessary.
No Go to next step.
15 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.
16 Measure gap between CKP sensor and teeth of
pulse wheel.
Specification
1.5—2.5 mm {0.059—0.098 in}
Is gap within specification?Yes Go to next step.
No Adjust CKP sensor position.
17 Visually inspect CMP sensor and teeth of pulse
wheel.
Are CMP sensor and teeth of pulse wheel okay?Yes Inspect following PIDs:
(See F2–65 PCM INSPECTION)
•ECT
•RPM
If PID value is not as specified, repair or replace
malfunctioning parts.
If PID value is okay, go to next step.
No Replace malfunctioning parts.
18 Inspect fuel pressure sensor.
(See F2–79 FUEL PRESSURE SENSOR
INSPECTION)
Is fuel pressure okay?Yes Go to next step.
No Replace common rail.
19 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)
20 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.
21 Inspect fuel injector.
(See F2–56 FUEL INJECTOR INSPECTION)
Is fuel injector okay?Yes Go to next step.
No Repair or replace as necessary.
22 Inspect IDM.
(See F2–84 INJECTOR DRIVER MODULE
(IDM) INSPECTION)
Is IDM okay?Yes Go to next step.
No Repair or replace as necessary.
23 Inspect EGR system operation.
Is EGR system operation normal?Yes Remove and inspect supply pump and common rail.
No Repair or replace malfunctioning part according to
EGR system operation results.
24 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

F2–186
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.

F2–188
TROUBLESHOOTING
End Of Sie
13 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.
14 Inspect fuel injector.
(See F2–56 FUEL INJECTOR INSPECTION)
Is fuel injector okay?Yes Go to next step.
No Repair or replace as necessary.
15 Inspect EGR system operation.
Is EGR system operation normal?Yes Go to next step.
No Repair or replace malfunctioning part according to
EGR system operation results.
16 Inspect EGR water cooler for following:
•Coolant passage clogging/restriction
•Exhaust gas clogging/restriction
Is EGR water cooler okay?Yes Go to next step.
No Service as necessary.
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

F2–190
TROUBLESHOOTING
NO.10 LOW IDLE/STALLS DURING DECELERATIONA6E408018881212
Diagnostic Procedure
10 LOW IDLE/STALLS DURING DECELERATION
DESCRIPTION•Engine stops unexpectedly at beginning of deceleration or recovery from deceleration.
POSSIBLE
CAUSE•Intake-air system restriction or clogging
•Poor fuel quality
•A/C system improper operation
•Inadequate fuel pressure
•Suction control valve malfunction (built-in supply pump)
•Fuel pressure limiter malfunction (built-in common rail)
•Fuel leakage
•Fuel line restriction or clogging
•Fuel filter restriction or clogging
•Incorrect fuel injection timing
•Incorrect idle speed
•Erratic signal from CKP sensor
•Erratic signal from CMP sensor
•Supply pump malfunction
•Fuel injector malfunction
•Low engine compression
•Improper valve timing
•Glow system malfunction
•EGR system malfunction
•MAF/IAT sensor or related circuit malfunction
•ECT sensor or related circuit malfunction
•Fuel pressure sensor or related circuit malfunction
•Neutral switch malfunction or related circuit malfunction
•Accelerator position sensor or related circuit malfunction
•Idle switch or related circuit malfunction
•Incorrect adjustment accelerator position sensor and/or idle switch
•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 Does engine idle rough? Yes Go to symptom troubleshooting “NO.8 ENGINE RUNS
ROUGH/ROLLING IDLE”.
No Go to next step.
2 Inspect for following:
•Fuel line/fuel filter clogging or restriction
•Intake-air system restriction or clogging
•Fuel quality (e.g.: include water
contamination, winter/summer blend)
Are all items okay?Yes Go to next step.
No Service as necessary.
Repeat Step 2.
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 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
F2–191
F2
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 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)
6 Measure voltage PCM terminal 33 and 56.
Is voltage okay?Yes Go to next step.
NoPCM terminal 33 does not specified:
Inspect clutch switch and related harness.
PCM terminal 56 does not specified:
Inspect neutral switch and related harness.
7 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.
8 Measure gap between CKP sensor and teeth of
pulse wheel.
Specification
1.5—2.5 mm {0.059—0.098 in}
Is gap within specification?Yes Go to next step.
No Adjust CKP sensor position.
9 Visually inspect CMP sensor and teeth of pulse
wheel.
Are CMP sensor and teeth of pulse wheel okay?Yes Inspect following PIDs:
(See F2–65 PCM INSPECTION)
•ECT
•IAT
•MAF
•RPM
If PID value is not as specified, repair or replace
malfunctioning parts.
If PID value is okay, go to next step.
No Replace malfunctioning parts.
10 Inspect fuel pressure sensor.
(See F2–79 FUEL PRESSURE SENSOR
INSPECTION)
Is fuel pressure okay?Yes Go to next step.
No Replace common rail.
11 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)
12 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.
13 Inspect fuel injector.
(See F2–56 FUEL INJECTOR INSPECTION)
Is fuel injector okay?Yes Go to next step.
No Repair or replace as necessary.
14Note
•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
15 Inspect EGR system operation.
Is EGR system operation normal?Yes Go to next step.
No Repair or replace malfunctioning part according to
EGR system operation results.
16 Inspect glow system operation.
(See T–19 RELAY INSPECTION)
Is glow system operation normal?Yes Go to next step.
No Service as necessary. STEP INSPECTION RESULTS ACTION

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.