Mazda CX 7. Manual — part 34

ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–91

01-02

3

VERIFY RELATED PENDING AND STORED
DTC

• Turn the ignition switch off, then to the ON

position (Engine off).

• Verify pending and/or stored DTCs using the

M-MDS.

• Is DTC P0443 also present?

Yes

Go to DTC P0443 troubleshooting procedures, then go to
Step 13.

No

Go to the next step.

4

IDENTIFY TRIGGER DTC FOR FREEZE FRAME
DATA

• Is DTC P0139 on the FREEZE FRAME DATA?

Yes

Go to the next step.

No

Go to troubleshooting procedures for the DTC on the
FREEZE FRAME DATA.
(See01-02-13 DTC TABLE[L3 WITH TC].)

5

VERIFY CURRENT INPUT SIGNAL STATUS

• Warm up the engine.

• Access the O2S12 PID using the M-MDS.

• Inspect the PID under the following accelerator

pedal conditions or NEUTRAL.

• Is the PID normal?

— More than 0.55 V the accelerator pedal is

suddenly depressed (rich condition).

— Less than 0.55 V just after accelerator

pedal is released (lean condition).

Yes

Go to Step 8.

No

Go to the next step.

6

INSPECT INSTALLATION OF REAR HO2S

• Inspect if the rear HO2S is loosely installed.

• Is the sensor installed securely?

Yes

Go to the next step.

No

Retighten the sensor, then go to Step 13.

7

INSPECT GAS LEAKAGE FROM EXHAUST
SYSTEM

• Visually inspect if there is any gas leakage

between the exhaust manifold and the rear
HO2S.

• Is there gas leakage?

Yes

Repair or replace the malfunctioning faulty exhaust part,
then go to Step 13.

No

Replace sensor, then go to Step 13.

8

INSPECT LONG TERM FUEL TRIM

• Access the LONGFT1 PIDs

• Compare it with the FREEZE FRAME DATA

recorded at Step 1.

• Is it below the FFD value?

Yes

The engine is driven under a rich condition. Go to the next
step.

No

The engine is driven under a lean condition. Go to Step 10.

9

INSPECT FUEL LINE PRESSURE (Excessive
fuel line pressure)

• Turn the ignition switch off.

• Inspect the fuel line pressure while the engine

is running.
(See01-14-5 FUEL LINE PRESSURE
INSPECTION[L3 WITH TC].)

• Is the fuel line pressure normal?

Yes

Go to Step 12.

No

Inspect fuel pump maximum pressure and fuel return pipe
for clogging.
(See01-14-13 FUEL PUMP UNIT INSPECTION[L3 WITH
TC].)

• If there is any problem, repair or replace the parts.

• If all items above are normal, replace the fuel pump

unit.

Then go to Step 13.

10

INSPECT FUEL LINE PRESSURE (Low fuel line
pressure)

• Turn the ignition switch off.

• Inspect the fuel line pressure while the engine

is running.
(See01-14-5 FUEL LINE PRESSURE
INSPECTION[L3 WITH TC].)

• Is the fuel line pressure normal?

Yes

Go to Step 12.

No

Go to the next step.

11

INSPECT FUEL LINE FROM FUEL PUMP TO
FUEL DELIVERY PIPE

• Visually inspect the fuel line for any leakage.

• Is there fuel leakage?

Yes

Replace the fuel line, then go to Step 13.

No

Inspect the fuel filters for the following:

• Foreign material or staining inside the fuel filter (low-

pressure side)

Perform the following actions according to the result.

• If foreign material or staining is found inside fuel filter

(low-pressure side), clean the fuel tank and filter.

• If normal, replace fuel pump unit.

Then go to Step 13.

STEP

INSPECTION

ACTION

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ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–92

End Of Sie

DTC P0140[L3 WITH TC]

id010239805300

12

INSPECT SEALING OF ENGINE COOLANT
PASSAGE

• Perform the “ENGINE COOLANT LEAKAGE

INSPECTION.”
(See01-12-6 ENGINE COOLANT LEAKAGE
INSPECTION[L3 WITH TC].)

• Is there any malfunction?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to
inspection results.
Then go to the next step.

13

VERIFY TROUBLESHOOTING OF DTC P0139
COMPLETED

• Make sure to reconnect all disconnected

connectors.

• Turn the ignition switch to the ON position.

(Engine off)

• Clear the DTC from the memory using the M-

MDS.

• Perform the “PCM Adaptive Memory Produce

Drive Mode” and “HO2S heater, HO2S, and
TWC Repair Verification Drive Mode”.
(See01-02-10 OBD-II DRIVE MODE[L3 WITH
TC].)

• Is the PENDING CODE for this DTC present?

Yes

Replace the PCM, then go to the next step.
(See01-40-6 PCM REMOVAL/INSTALLATION[L3 WITH
TC].)

No

Go to the next step.

14

VERIFY AFTER REPAIR PROCEDURE

• Perform the “AFTER REPAIR PROCEDURE”.

(See01-02-10 AFTER REPAIR
PROCEDURE[L3 WITH TC].)

• Are any DTCs present?

Yes

Go to the applicable DTC troubleshooting.
(See01-02-13 DTC TABLE[L3 WITH TC].)

No

Troubleshooting completed.

STEP

INSPECTION

ACTION

DTC P0140

Rear HO2S no activity detected

DETECTION

CONDITION

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

following monitoring conditions, if the input voltage from the rear HO2S does not even exceed 0.55 V
though the short term fuel trim is controlled up to 20.5% for 9.6 s, the PCM determines that sensor circuit is
not activated.

MONITORING CONDITIONS

— HO2S, HO2S heater and TWC repair verification drive mode

— The following conditions are met for above 20.8 s.

• Engine speed is above 1,500 rpm.

• Engine coolant temperature is above 70 °C {158 °F}.

• Rear HO2S voltage is above0.1V.

Diagnostic support note

• This is an intermittent monitor (HO2S).

• The MIL illuminates if the 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 the PCM detects the above malfunction condition during first drive cycle.

• FREEZE FRAME DATA is available.

• DTCs are stored in the PCM memory.

POSSIBLE

CAUSE

• Rear HO2S deterioration

• Rear HO2S heater malfunction

• Exhaust system leakage

• Open circuit or short to ground in the wiring harness between rear HO2S terminal A and PCM terminal 2Q

• Insufficient compression

• Engine malfunction

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ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–93

01-02

Diagnostic procedure

STEP

INSPECTION

ACTION

1

VERIFY FREEZE FRAME DATA AND
DIAGNOSTIC MONITORING TEST RESULTS
HAVE BEEN RECORDED

• Have the FREEZE FRAME DATA and

DIAGNOSTIC MONITORING TEST RESULTS
(HO2S related) been recorded?

Yes

Go to the next step.

No

Record the FREEZE FRAME DATA and DIAGNOSTIC
MONITORING TEST RESULTS on the repair order, then
go to the next step.

2

VERIFY RELATED REPAIR INFORMATION
AVAILABILITY

• Verify related Service Bulletins and/or on-line

repair information availability.

• Is any related repair information available?

Yes

Perform the repair or diagnosis according to the available
repair information.

• If the vehicle is not repaired, go to the next step.

No

Go to the next step.

3

VERIFY RELATED PENDING AND STORED
DTC

Note

• If the fuel monitor, DTC P0132 is retrieved,

ignore it until P0140 is fixed.

• Turn the ignition switch off, then to the ON

position. (Engine off)

• Verify pending and stored DTCs using the M-

MDS.

• Are other DTCs present?

Yes

Go to the appropriate DTC troubleshooting procedures.
(See01-02-13 DTC TABLE[L3 WITH TC].)

No

Go to the next step.

4

IDENTIFY TRIGGER DTC FOR FREEZE FRAME
DATA

• Is DTC P0140 on the FREEZE FRAME DATA?

Yes

Go to the next step.

No

Go to troubleshooting procedures for the DTC on the
FREEZE FRAME DATA.
(See01-02-13 DTC TABLE[L3 WITH TC].)

DTC P0140

Rear HO2S no activity detected

REAR HO2S

PCM

WIRING HARNESS-SIDE CONNECTOR

REAR HO2S

WIRING HARNESS-SIDE CONNECTOR

7

PCM

A

B

2Q

1BC

2BE 2BA 2AW 2AS 2AO 2AK 2AG 2AC 2Y 2U 2Q 2M

2E

2A

2I

2BH 2BD 2AZ 2AV 2AR 2AN 2AJ 2AF 2AB 2X 2T 2P

2H

2D

2L

2BG 2BC 2AY 2AU 2AQ 2AM 2AI 2AE 2AA 2W 2S 2O

2G

2C

2K

2BF 2BB 2AX 2AT 2AP 2AL 2AH 2AD 2Z

2V 2R 2N

2F

2B

2J

1BE 1BA 1AW 1AS 1AO 1AK 1AG 1AC 1Y 1U 1Q 1M

1E

1A

1I

1BH 1BD 1AZ 1AV 1AR 1AN 1AJ 1AF 1AB 1X

1T

1P

1H

1D

1L

1BG 1BC 1AY 1AU 1AQ 1AM 1AI 1AE 1AA 1W 1S 1O

1G

1C

1K

1BF 1BB 1AX 1AT 1AP 1AL 1AH 1AD 1Z

1V

1R 1N

1F

1B

1J

A

B

C

D

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ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–94

End Of Sie

5

VERIFY CURRENT INPUT SIGNAL STATUS

• Warm up the engine.

• Access the O2S12 or the P0140 PID using the

M-MDS.

• Verify the PID while racing the engine at least

10 times in NEUTRAL.

• Is the PID reading normal?

— More than 0.55 V at least once during

engine racing

Yes

Go to Step 8.

No

Go to the next step.

6

INSPECT INSTALLATION OF REAR HO2S

• Check if the rear HO2S is loosely installed.

• Is the sensor installed securely?

Yes

Go to the next step.

No

Install the sensor securely, then go to Step 10.

7

INSPECT GAS LEAKAGE FROM EXHAUST
SYSTEM

• Visually check if any gas leakage is found

between the exhaust pipe and the rear HO2S.

• Is there gas leakage?

Yes

Repair or replace any malfunctioning exhaust part, then go
to Step 10.

No

• Inspect the following wiring harness for an open or short

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

terminal 2Q (wiring harness-side)

• Repair or replace the wiring harness if necessary.

• If all items above are normal, replace the malfunctioning

sensor.

Then go to Step 10.

8

INSPECT SEALING OF ENGINE COOLANT
PASSAGE

• Perform the ENGINE COOLANT LEAKAGE

INSPECTION.
(See01-12-6 ENGINE COOLANT LEAKAGE
INSPECTION[L3 WITH TC].)

• Is the cooling system hold pressure normal?

Yes

Repair or the replace the malfunctioning part according to
the inspection result.
Then go to Step 10.

No

Go to the next step.

9

INSPECT ENGINE COMPRESSION

• Inspect the engine compression.

(See01-10-9 COMPRESSION
INSPECTION[L3 WITH TC].)

• Is it normal?

Yes

Go to the next step.

No

Perform engine overhaul for repairs, then go to the next
step.

10

VERIFY TROUBLESHOOTING OF DTC P0140
COMPLETED

• Make sure to reconnect all disconnected

connectors.

• Turn the ignition switch to the ON position.

(Engine off)

• Clear the DTC from the memory using the M-

MDS.

• Perform the HO2S heater, HO2S, and TWC

Repair Verification Drive Mode.
(See01-02-10 OBD-II DRIVE MODE[L3 WITH
TC].)

• Is the PENDING CODE for this DTC present?

Yes

Replace the PCM, then go to the next step.
(See01-40-6 PCM REMOVAL/INSTALLATION[L3 WITH
TC].)

No

Go to the next step.

11

VERIFY AFTER REPAIR PROCEDURE

• Perform the “AFTER REPAIR PROCEDURE”.

(See01-02-10 AFTER REPAIR
PROCEDURE[L3 WITH TC].)

• Are any DTCs present?

Yes

Go to the applicable DTC troubleshooting.
(See01-02-13 DTC TABLE[L3 WITH TC].)

No

Troubleshooting completed.

STEP

INSPECTION

ACTION

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