Mazda CX 7. Manual - part 32

ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–83

01-02

End Of Sie

DTC P0134[L3 WITH TC]

id010239804900

14

VERIFY TROUBLESHOOTING OF DTC P0133 
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.

15

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 P0134

Front HO2S no activity detected

DETECTION 

CONDITION

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

following monitoring conditions, the input voltage more than 3.22 V, the PCM determines that the front 
HO2S is not activated.

MONITORING CONDITIONS

— HO2S, HO2S heater and TWC Repair Verification Drive Mode

— The following conditions are met

• Front HO2S heater is tuned on for above 30 s

• Battery voltage: 10— 18 V

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

• Front HO2S deterioration

• Front HO2S heater malfunction

• Leakage exhaust system

• Open or short circuit in the wiring harness between front HO2S terminal 2D and PCM terminal 2C

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

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

• Open or short circuit in the wiring harness between front HO2S terminal 1A and PCM terminal 2AD

• Insufficient compression

• Engine malfunction

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ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–84

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 fuel monitor, DTC P0132 is retrieved, 

ignore it until P0134 is fixed.

• Turn the ignition switch off, then to the ON 

position. (Engine off)

• Verify pending and stored DTCs using the M-

MDS.

• Is the DTC P2237 or P2251 also present?

Yes

Go to the appropriate DTC troubleshooting procedures.

No

Go to the next step.

DTC P0134

Front HO2S no activity detected

FRONT HO2S HEATER

2C

PCM

PCM

WIRING HARNESS-SIDE CONNECTOR

2B

2D

MAIN RELAY

1A

1B

1C

1D

2A

2B

2C

2D

FRONT HO2S

WIRING HARNESS-SIDE CONNECTOR

7

FRONT HO2S 

1B

1A

2AC

2AD

2Z

1C

7

7

7

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]

01-02–85

01-02

End Of Sie

4

IDENTIFY TRIGGER DTC FOR FREEZE FRAME 
DATA

• Is DTC P0134 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 O2S11 PID using the M-MDS.

• Verify the PID while racing engine in 

NEUTRAL.

• Is the PID normal?

— –1.0— 1.0 A when idle

— More than 0.25 mA just after releasing the 

of accelerator pedal is released (lean 
condition)

Yes

Go to Step 8.

No

Go to the next step.

6

INSPECT INSTALLATION OF FRONT HO2S

• Inspect if the front 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 EXHAUST SYSTEM FOR GAS 
LEAKAGE

• Visually inspect if there is any gas leakage 

between the exhaust manifold and front HO2S.

• Is there gas leakage?

Yes

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

No

• Inspect the following wiring harnesses at the wiring 

harness-side connector terminals for an open circuit, 
repair or the replace wiring harness if necessary.
— Front HO2S terminal 1A and PCM terminal 2AD

— Front HO2S terminal 1B and PCM terminal 2AC

— Front HO2S terminal 1C and PCM terminal 2Z

— Front HO2S terminal 2D and PCM terminal 2C

• If all the 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 there any malfunction?

Yes

Repair or replace the malfunctioning part according to the 
inspection results, 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 the engine overhaul for repairs, then go to the next 
step.

10

VERIFY TROUBLESHOOTING OF DTC P0134 
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 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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ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–86

DTC P0137[L3 WITH TC]

id010239805000

DTC P0137

Rear HO2S circuit low input

DETECTION 

CONDITION

• The PCM monitors the input voltage from the rear HO2S. If the input voltage from the rear HO2S sensor 

is below 0.1 V for 41.6 s, the PCM determines that the circuit input is low.

MONITORING CONDITIONS

— HO2S,HO2S heater and TWC repair verification drive mode.

— The following conditions are met.

• Engine speed is above 1,500 rpm.

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

• Fuel injector control in rear HO2S is in closed loop control.

• 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 exceed 0.1 V 
through the short term fuel trim is controlled up to 20.5% for 9.6 s, the PCM determines that the sensor 
circuit input is low.

MONITORING CONDITIONS

— HO2S,HO2S heater and TWC repair verification drive mode.

— The following conditions are met for more than 20.8 s.

• Engine speed is more than 1,500 rpm.

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

Diagnostic support note

• This is an intermittent monitor (HO2S).

• The MIL illuminates if the PCM detects the above malfunctioning 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.

• DTCs are stored in the PCM memory.

POSSIBLE 

CAUSE

• Rear HO2S malfunction

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

• PCM malfunction

REAR HO2S 

PCM

WIRING HARNESS-SIDE CONNECTOR

REAR HO2S

WIRING HARNESS-SIDE CONNECTOR

5

PCM

A

B

2Q

1BC

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

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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