Mazda CX-9 Grand Touring. Manual - part 213

Fig. 28: Identifying HO2S Connector 
Courtesy of MAZDA MOTORS CORP. 

CIRCUIT OPEN/SHORT INSPECTION 

1. Disconnect the PCM connector. (See PCM REMOVAL/INSTALLATION [MZI-3.7].)  

2. Inspect the following wiring harness for open or short (continuity check). 

 

2008 Mazda CX-9 Grand Touring 

2008 ENGINE Control System (MZI-3.7) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:07:19 AM

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Fig. 29: Identifying PCM Warning Harness-Side Connector 
Courtesy of MAZDA MOTORS CORP. 

Open circuit 



If there is no continuity, the circuit is open. Repair or replace the harness. 



HO2S (RH) terminal A and PCM terminal 2J  



HO2S (RH) terminal B and PCM terminal 2Y  



HO2S (RH) terminal C and main relay No.2 terminal D  



HO2S (RH) terminal D and PCM terminal 2AL  



HO2S (LH) terminal A and PCM terminal 2E  



HO2S (LH) terminal B and PCM terminal 2U  



HO2S (LH) terminal C and main relay No.2 terminal D  



HO2S (LH) terminal D and PCM terminal 2AL  

Short circuit 

 

2008 Mazda CX-9 Grand Touring 

2008 ENGINE Control System (MZI-3.7) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:07:19 AM

Page 32 

© 2005 Mitchell Repair Information Company, LLC. 



If there is continuity, the circuit is shorted. Repair or replace the harness. 



HO2S (RH) terminal A and power supply  



HO2S (RH) terminal A and body ground  



HO2S (RH) terminal B and power supply  



HO2S (RH) terminal B and body ground  



HO2S (RH) terminal C and body ground  



HO2S (RH) terminal D and power supply  



HO2S (LH) terminal A and power supply  



HO2S (LH) terminal A and body ground  



HO2S (LH) terminal B and power supply  



HO2S (LH) terminal B and body ground  



HO2S (LH) terminal C and body ground  



HO2S (LH) terminal D and power supply  

REAR HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [MZI-
3.7] 

HO2S (LH) REMOVAL/INSTALLATION 

1. Disconnect the negative battery cable.  

2. Disconnect the HO2S (LH) connector. 

3. Remove the HO2S (LH) using the SST. 

4. Install in the reverse order of removal. 

NOTE:



If necessary, lubricate the HO2S (LH) with Penetrating and Lock 
Lubricant loosen to aid in removal.  

NOTE:



Apply a light coat of anti-seize lubricant to the threads of the HO2S. 

 

2008 Mazda CX-9 Grand Touring 

2008 ENGINE Control System (MZI-3.7) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:07:19 AM

Page 33 

© 2005 Mitchell Repair Information Company, LLC. 

Fig. 30: View Of HO2S, SST & Torque Specifications
Courtesy of MAZDA MOTORS CORP. 

HO2S (RH) REMOVAL/INSTALLATION 

1. Disconnect the negative battery cable.  

2. Remove the following part for easier access. 

1. Remove the cowl panel. (See COWL PANEL REMOVAL/INSTALLATION .)  

3. Disconnect the HO2S (RH) connector. 

4. Remove the HO2S (RH) using the SST. 

5. Install in the reverse order of removal. 

Fig. 31: View Of HO2S, SST & Torque Specifications 
Courtesy of MAZDA MOTORS CORP. 

REAR HEATED OXYGEN SENSOR (HO2S) INSPECTION [MZI-3.7] 

REAR HEATED OXYGEN SENSOR (HO2S) VOLTAGE INSPECTION 

1. Warm up the engine to normal operating temperature.  

2. Using the M-MDS, monitor the following: 



Vehicle speed (PID: VSS)  

NOTE:



If necessary, lubricate the HO2S (RH) with Penetrating and Lock 
Lubricant loosen to aid in removal.  

NOTE:



Apply a light coat of anti-seize lubricant to the threads of the HO2S. 

NOTE:



Before performing the following inspection, make sure to follow the 
procedure as indicated in the troubleshooting flowchart. (See HOW TO 
USE THIS MANUAL .)  

 

2008 Mazda CX-9 Grand Touring 

2008 ENGINE Control System (MZI-3.7) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:07:19 AM

Page 34 

© 2005 Mitchell Repair Information Company, LLC.