Mazda CX 7. Manual — part 30

ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–75

01-02

5

VERIFY MONITORING CONDITION FOR
REPAIR VERIFICATION

• Make sure to reconnect all disconnected

connectors.

• Cool down engine.

Note

• If workshop inside and outside

temperature difference is significant,
PCM might not operate thermostat
monitor. Therefore, it is recommended to
cool down engine out of workshop.

• Turn ignition switch to ON (Engine off).

• Clear the DTC from the PCM memory using

the M-MDS.

• Access ECT, IAT PIDs and make sure that

each value is within following specifications.
— ECT: below 36 °C {97 °F} (for P0128 only)

— IAT: above –10°C {14°F}

— Difference between ECT and IAT: below

6°C {43°F}

• Is there any PID that is out of specification?

Yes

Take corrective action (e.g. cool down engine), then repeat
this step.

No

Go to the next step for DTC P0126 or go to step 7 for DTC
P0128.

6

VERIFY TROUBLESHOOTING OF DTC P0126
COMPLETED

• Start engine and turn off E/L and A/C.

• Access DIAGNOSTIC MONITORING TEST

RESULTS using the M-MDS and monitor TEST
#10: E1: 81 (ECT).

Note

• This test requires actual driving. Chassis

roller cannot be used for this test.

• During test drive, constant speed should

be maintained, although 2 or 3 stops
during every5 minutes of driving time
(e.g. for traffic signals) is acceptable.
Stop-and-go (e.g. in case of traffic
congestion) is not acceptable during the
test period.

• Test period depends on ECT at engine

start. (e.g. if ECT is –10°C {14°F},
monitoring period is38 minutes and
ECT is 30 °C {86 °F}, monitoring period
is 8 minutes)

• Verify TEST #10: E1: 81 (ECT) value.

• Is value above minimum value?

Yes

Go to Step 8.

No

Replace PCM, then go to Step 8.

STEP

INSPECTION

ACTION

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ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–76

End Of Sie

DTC P0131[L3 WITH TC]

id010239804600

7

VERIFY TROUBLESHOOTING OF DTC P0128
COMPLETED

• Start engine and turn off E/L and A/C.

• Access DIAGNOSTIC MONITORING TEST

RESULTS using the M-MDS and monitor TEST
#10: E1: 80 (Heat radiation ratio) or #10: E1: 81
(ECT).

Note

• This test requires actual driving. Chassis

roller cannot be used for this test.

• During test drive, constant speed should

be maintained, although 2 or 3 stops
(e.g. for traffic signals) is acceptable.
Stop-and-go (e.g. in case of traffic
congestion) is not acceptable during the
test period.

• Verify TEST #10: E1: 80 (Heat radiation ratio)

and #10: El: 81 (ECT) value.

• Are value of TEST #10: E1: 80 (Heat radiation

ratio) below maximum value and value of TEST
#10: E1: 81 (ECT) above minimum value?

Yes

Go to the next step.

No

Replace PCM, then go to the next step.

8

VERIFY AFTER REPAIR PROCEDURE

• Perform the “After Repair Procedure”.

• Is any DTC present?

Yes

Go to the applicable DTC inspection.

No

Troubleshooting completed.

STEP

INSPECTION

ACTION

DTC P0131

Front HO2S circuit low input

DETECTION

CONDITION

• The PCM monitors the input voltage from the front HO2S when the engine is running. If the input voltage is

above 1.0 V for 25 s, the PCM determines that the front HO2S circuit voltage is low.

Diagnostic support note

• This is a continuance 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 the first drive

cycle.

• FREEZE FRAME DATA is available.

• DTCs are stored in the PCM memory.

POSSIBLE

CAUSE

• Front HO2S malfunction

• Connector or terminal malfunction

• Open circuit in the wiring harness between front HO2S terminal 1C and PCM terminal 2Z

• Short to ground in the wiring harness between front HO2S terminal 1C and PCM terminal 2Z

• Open circuit in the wiring harness between front HO2S terminal 1B and PCM terminal 2AC

• Short to ground in the wiring harness between front HO2S terminal 1B and PCM terminal 2AC

• Short to ground in the wiring harness between front HO2S terminal 1A and PCM terminal 2AD

• PCM malfunction

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ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–77

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 OR STORED DTC

• Turn the ignition switch off, then to the ON

position (Engine off).

• Verify the pending code or 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 P0131 on 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

INSPECT FRONT HO2S CONNECTOR FOR
POOR CONNECTION

• Turn the ignition switch off.

• Disconnect the front HO2S connector.

• Inspect for poor connection (such as damaged/

pulled-out pins, corrosion).

• Is there any malfunction?

Yes

Repair or replace the terminal, then go to Step 10.

No

Go to the next step.

DTC P0131

Front HO2S circuit low input

FRONT HO2S

PCM

WIRING HARNESS-SIDE CONNECTOR

1A

1B

1C

1D

2A

2B

2C

2D

FRONT HO2S

WIRING HARNESS-SIDE CONNECTOR

8

7

5

8

5

6

PCM

1B

1A

2AC

2AD

9

6 9

2Z

1C

8

5

9

6

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

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ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–78

End Of Sie

6

INSPECT FRONT HO2S CIRCUIT FOR SHORT
TO GROUND

• Turn the ignition switch off.

• Inspect for continuity between the following

terminals and body ground:

— Front HO2S terminal 1A (wiring harness-

side) and body ground

— Front HO2S terminal 1B (wiring harness-

side) and body ground

— Front HO2S terminal 1C (wiring harness-

side) and body ground

• Is there continuity?

Yes

Repair or replace the wiring harness for a possible short to
ground, then go to Step 10.

No

Go to the next step.

7

INSPECT FRONT HO2S

• Inspect the front HO2S.

(See01-40-37 HEATED OXYGEN SENSOR
(HO2S) INSPECTION[L3 WITH TC].)

• Is there any malfunction?

Yes

Replace the front HO2S, then go to Step 10.
(See01-15-2 EXHAUST SYSTEM REMOVAL/
INSTALLATION[L3 WITH TC].)

No

Go to the next step.

8

INSPECT PCM CONNECTOR FOR POOR
CONNECTION

• Turn the ignition switch off.

• Disconnect the PCM connector.

• Inspect for poor connection (such as damaged/

pulled-out pins, corrosion).

• Is there any malfunction?

Yes

Repair or replace the terminal, then go to Step 10.

No

Go to the next step.

9

INSPECT FRONT HO2S CIRCUIT FOR OPEN
CIRCUIT

• Turn the ignition switch off.

• Inspect for continuity between the following

circuits:

— Front HO2S terminal 1B (wiring harness-

side) and PCM terminal 2AC (wiring
harness-side)

— Front HO2S terminal 1C (wiring harness-

side) and PCM terminal 2Z (wiring harness-
side)

• Is there continuity?

Yes

Go to the next step.

No

Repair or replace the wiring harness for a possible open
circuit, then go to the next step.

10

VERIFY TROUBLESHOOTING OF DTC P0131
COMPLETED

• Make sure to reconnect all disconnected

connectors.

• Clear the DTC from the PCM memory using

the M-MDS.

• Perform 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 inspection.
(See01-02-13 DTC TABLE[L3 WITH TC].)

No

DTC troubleshooting completed.

STEP

INSPECTION

ACTION

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