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Mazda 6. Manual - part 148

F–114

ON-BOARD DIAGNOSTIC

End Of Sie

DTC P0140

A6E397001084W26

VERIFY TROUBLESHOOTING OF DTC P0138
COMPLETED

• Make sure to reconnect all disconnected

connectors.

• Turn ignition key to ON (Engine OFF).

• Clear DTC from memory using WDS or

equivalent.

• Run PCM adaptive memory procedure drive

mode and HO2S heater, HO2S, and TWC
repair verification drive mode.
(See

F–64 OBD DRIVE MODE

• Is PENDING CODE the same as DTC

present?

Yes Replace PCM, then go to next step.

(See

F–43 PCM REMOVAL/INSTALLATION

Go to next step.

VERIFY AFTER REPAIR PROCEDURE

• Perform “After Repair Procedure”.

(See

F–66 AFTER REPAIR PROCEDURE

• Is there any DTC present?

Yes Go to applicable DTC troubleshooting.

(See

F–67 DTC TABLE

Troubleshooting completed.

STEP

INSPECTION

ACTION

DTC P0140

Rear HO2S circuit no activity detected

DETECTION

CONDITION

• PCM monitors input voltage from rear HO2S when the following conditions are met. If input voltage from

sensor never exceed 0.55 V for 30.4 s, PCM determines that sensor circuit is not activated.

MONITORING CONDITIONS

— HO2S, HO2S heater and TWC repair verification drive mode
— Following conditions are met:

• Engine speed is above 1,500 rpm.

• Engine coolant temperature is above 80 °C {158 °F}.

Diagnostic support note

• This is a continuous monitor (CCM).

• MIL illuminates if PCM detects the above malfunction condition in two consecutive drive cycles or in one

drive cycle while the DTC for the same malfunction has been stored in the PCM.

• PENDING CODE is available if PCM detects the above malfunction condition during first drive cycle.

• FREEZE FRAME DATA is available.

• DTC is stored in the PCM memory.

POSSIBLE

CAUSE

• Rear HO2S deterioration

• Rear HO2S heater malfunction

• Leakage exhaust system

• Open or short to ground circuit between rear HO2S terminal A and PCM terminal 1Y

• Insufficient compression

• Engine malfunction

ON-BOARD DIAGNOSTIC

F–115

Diagnostic procedure

STEP

INSPECTION

ACTION

PERFORM DTC CONFIRMATION PROCEDURE

• Perform DTC CONFIRMATION PROCEDURE.

(See

F–66 DTC CONFIRMATION

PROCEDURE

• Is same DTC present?

Yes Go to next step.

Intermittent concern exists. Go to INTERMITTENT
CONCERN TROUBLESHOOTING procedure.
(See

F–227 INTERMITTENT CONCERN

TROUBLESHOOTING

VERIFY RELATED PENDING AND STORED
DTCS

Note

• If fuel monitor DTC, DTC P0131or P0132 is

retrieved, ignore it until P0140 is fixed.

• Turn ignition key to OFF, then ON (Engine

OFF).

• Verify pending and stored DTCs using WDS or

equivalent.

• Is other DTC present?

Yes Go to appropriate DTC troubleshooting procedures.

(See

F–67 DTC TABLE

Go to next step.

IDENTIFY TRIGGER DTC FOR FREEZE FRAME
DATA

• Is DTC P0140 on FREEZE FRAME DATA?

Yes Go to next step.

Go to troubleshooting procedures for DTC on FREEZE
FRAME DATA.
(See

F–67 DTC TABLE

VERIFY CURRENT INPUT SIGNAL STATUS

• Warm up engine.

• Access O2S12 for P0140 or O2S22 for P0160

PID using WDS or equivalent.

• Verify PID while racing engine at least 10

times (in NEUTRAL (MTX) or PARK (ATX)).

• Is PID reading okay?

— More than 0.55 V at least once during

engine racing.

Yes Go to step 7.

Go to next step.

INSPECT INSTALLATION OF REAR HO2S

• Check if rear HO2S is loosely installed.

• Is sensor installed securely?

Yes Go to next step.

Install sensor securely, then go to Step 9.

DTC P0140

Rear HO2S circuit no activity detected

F–116

ON-BOARD DIAGNOSTIC

End Of Sie

DTC P0171

A6E397001084W27

INSPECT GAS LEAKAGE FROM EXHAUST
SYSTEM

• Visually check if any gas leakage is found

between exhaust pipe and rear HO2S.

• Is there any gas leakage?

Yes Repair or replace any faulty exhaust parts, then go to Step

• Inspect the following harnesses for open or short to

ground circuit, repair or replace harness if necessary.
— Rear HO2S terminal A (harness-side) to PCM

terminal 1Y (harness-side)

• Repair or replace harness if necessary.

• If all items above are okay, replace faulty sensor.

Then go to Step 9.

INSPECT SEALING OF ENGINE COOLANT
PASSAGE

Warning
• Removing radiator cap when radiator is

hot is dangerous. Scalding coolant and
steam may shoot out and cause serious
injury.

• When removing radiator cap, wrap a

thick cloth around and turn it slowly.

• Remove radiator cap.

• Implement procedure to bleed air from engine

coolant, then run engine at idle.

• Is there any small bubble, which makes engine

coolant white at filling opening?

Note

• Large bubbles are normal since they are

remaining air coming out from engine
coolant passage.

Yes Air gets in from poor sealing on head gasket or other areas

between combustion chamber and engine coolant
passage.
Repair or replace faulty parts, then go to Step 9.

Go to next step.

INSPECT ENGINE COMPRESSION

• Inspect engine compression.

(See

B–9 COMPRESSION INSPECTION

• Is it okay?

Yes Go to next step.

Implement engine overhaul for repairs, then go to next
step.

VERIFY TROUBLESHOOTING OF DTC P0140
COMPLETED

• Make sure to reconnect all disconnected

connectors.

• Turn ignition key to ON (Engine OFF).

• Clear DTC from memory using WDS or

equivalent.

• Perform KOER self-test.

(See

F–66 KOEO/KOER SELF-TEST

• Is same DTC present?

Yes Replace PCM, then go to next step.

(See

F–43 PCM REMOVAL/INSTALLATION

Go to next step.

VERIFY AFTER REPAIR PROCEDURE

• Perform “After Repair Procedure”.

(See

F–66 AFTER REPAIR PROCEDURE

• Is there any DTC present?

Yes Go to applicable DTC troubleshooting.

(See

F–67 DTC TABLE

Troubleshooting completed.

STEP

INSPECTION

ACTION

DTC P0171

Fuel trim system too lean

DETECTION

CONDITION

• PCM monitors short term fuel trim (SHRTFT) and long term fuel trim (LONGFT) values during closed loop

fuel control. If fuel trim exceeds preprogrammed criteria, PCM determines that fuel system is too lean.

Diagnostic support note

• This is a continuous monitor. (FUEL SYSTEM)

• MIL illuminates if PCM detects the above malfunction condition in two consecutive drive cycles or in one

drive cycle while the DTC for the same malfunction has been stored in the PCM.

• PENDING CODE is available if PCM detects the above malfunction conditions during first drive cycle.

• FREEZE FRAME DATA is available.

• DTC is stored in the PCM memory.

ON-BOARD DIAGNOSTIC

F–117

Diagnostic procedure

POSSIBLE

CAUSE

• Misfire

• Front HO2S deterioration

• Front HO2S heater malfunction

• Pressure regulator malfunction

• Fuel pump malfunction

• Fuel filter clogged or restricted

• Fuel leakage on fuel line from fuel delivery pipe and fuel pump

• Fuel return hose clogged

• Leakage exhaust system

• Purge solenoid valve malfunction

• Purge solenoid hoses improper connection

• Insufficient compression

• Variable valve timing control system improper operation (L3-VE)

STEP

INSPECTION

ACTION

PERFORM DTC CONFIRMATION PROCEDURE

• Perform DTC CONFIRMATION PROCEDURE.

(See

F–66 DTC CONFIRMATION

PROCEDURE

• Is same DTC present?

Yes Go to next step.

Intermittent concern exists. Go to INTERMITTENT
CONCERN TROUBLESHOOTING procedure.
(See

F–227 INTERMITTENT CONCERN

TROUBLESHOOTING

VERIFY RELATED PENDING CODE OR
STORED DTCS

• Turn ignition key to OFF, then ON (Engine

OFF).

• Verify related PENDING CODE or stored

DTCs.

• Is other DTCs present?

Yes If misfire DTC is present, go to step 7.

If other DTC is present, go to appropriate DTC
troubleshooting procedures.
(See

F–67 DTC TABLE

If drive ability concern is present, go to Step 7.
If not, go to next step.

IDENTIFY TRIGGER DTC FOR FREEZE FRAME
DATA

• Is DTC P0171 on FREEZE FRAME DATA?

Yes Go to next step.

Go to troubleshooting procedures for DTC on FREEZE
FRAME DATA.

VERIFY CURRENT INPUT SIGNAL STATUS
(IGNITION KEY TO ON/IDLE)

• Access ECT, MAF, TP and VSS PIDs using

WDS or equivalent.
(See

F–45 PCM INSPECTION

• Is there any signal that is far out of

specification when ignition key is ON and
engine runs?

Yes Inspect suspected sensor and excessive resistance in

related wiring harnesses. Repair or replace if necessary.
Then go to Step 18.

Go to next step.

VERIFY CURRENT INPUT SIGNAL STATUS
UNDER TROUBLE CONDITION

• Inspect same PIDs as Step 4 while simulating

FREEZE FRAME DATA condition.

• Is there any input signal which causes drastic

changes?

Yes Inspect suspected sensor and related wiring harnesses,

and repair or replace it. Then go to Step 18.

Go to next step.

VERIFY CURRENT INPUT SIGNAL STATUS OF
FRONT HO2S

• Access O2S11 for P0171 PID using WDS or

equivalent.

• Check PID under following accelerator pedal

condition (in PARK (ATX) or NEUTRAL
(MTX)).

• Is PID reading okay?

— Above 0.55 V when accelerator pedal is

suddenly depressed (rich condition).

— Below 0.55 V just after release of

accelerator pedal (lean condition)

Yes Inspect for air suction at followings due to cracks, damages

and loosening parts:

• From air cleaner to throttle body

• From throttle body to dynamic chamber

• From dynamic chamber to intake manifold

• Vacuum hoses

Note

• Engine speed may change when rust penetrating

agent is sprayed on the air suction area.

Repair or replace any faulty part, then go to Step 18.

Visually inspect for any gas leakage between exhaust
manifold and front HO2S.

• If there is no leakage, replace FRONT HO2S.

Then go to Step 18.

DTC P0171

Fuel trim system too lean

Content .. 146 147 148 149 ..