Mazda CX-9 Grand Touring. Manual - part 214



Engine speed (PID: RPM)  



Rear HO2S voltage (PID: O2S12, O2S22)  

3. Drive the vehicle and decelerate the engine speed by releasing the accelerator pedal fully when the engine 

speed is 3,000 rpm or more.  

4. Verify that the rear HO2S outputs a voltage of 0.6 V or more , one time or more, then verify that the rear 

HO2S voltage (PID: O2S12, O2S22) is 0.3 V is or less while decelerating as shown in the figure. 

Fig. 32: Output Voltage Graph 
Courtesy of MAZDA MOTORS CORP. 



If not within the specification, inspect the rear HO2S for an open or short circuit. Then if there is no 
malfunction in the wiring harness, replace the rear HO2S. (See REAR HEATED OXYGEN 
SENSOR (HO2S) REMOVAL/INSTALLATION [MZI-3.7].)  

HO2S HEATER RESISTANCE INSPECTION 

1. Disconnect the HO2S connector.  

2. Measure the resistance between HO2S terminals C and A. 



If it is not within the specification, replace the HO2S. (See REAR HEATED OXYGEN SENSOR 
(HO2S) REMOVAL/INSTALLATION [MZI-3.7].)  



If the monitor item status/specification (reference) is not within the specification, even though the 
resistance is within the specification, perform the "Circuit Open/Short Inspection".  

HO2S heater resistance  

 

2008 Mazda CX-9 Grand Touring 

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

  

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3-30 ohms  

Fig. 33: 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

  

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Fig. 34: Identifying PCM Wiring Harness-Side Connector And Rear HO2S Connector 
Courtesy of MAZDA MOTORS CORP. 

Open circuit 



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

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HO2S (RH) terminal A and PCM terminal 2AS  

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HO2S (RH) terminal B and PCM terminal 2BG  

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

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HO2S (RH) terminal D and PCM terminal 2AL  

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HO2S (LH) terminal A and PCM terminal 2AO  

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HO2S (LH) terminal B and PCM terminal 2BC  

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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

  

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

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



HO2S (RH) terminal A and power supply  

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HO2S (RH) terminal A and body ground  

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HO2S (RH) terminal B and power supply  

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HO2S (RH) terminal B and body ground  

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HO2S (RH) terminal C and body ground  

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HO2S (RH) terminal D and power supply  

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HO2S (LH) terminal A and power supply  

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HO2S (LH) terminal A and body ground  

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HO2S (LH) terminal B and power supply  

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HO2S (LH) terminal B and body ground  

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HO2S (LH) terminal C and body ground  



HO2S (LH) terminal D and power supply  

KNOCK SENSOR (KS) REMOVAL/INSTALLATION [MZI-3.7] 

1. Disconnect the negative battery cable.  

2. Remove the following part for easier access. Perform the following procedure to remove the intake 

manifold 

1. Remove the ventilation hose. (See QUICK RELEASE CONNECTOR (EMISSION SYSTEM) 

REMOVAL/INSTALLATION [MZI-3.7] .)  

2. Remove the vacuum hose (to purge solenoid valve). (See QUICK RELEASE CONNECTOR 

(EMISSION SYSTEM) REMOVAL/INSTALLATION [MZI-3.7] .)  

3. Remove the fuel hose. (See QUICK RELEASE CONNECTOR REMOVAL/INSTALLATION 

[MZI-3.7] .)  

4. Remove the fuel distributor. (See FUEL INJECTOR REMOVAL/INSTALLATION [MZI-

3.7] .)  

5. Remove the intake manifold. (See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION 

[MZI-3.7] .) 

NOTE:



Put a tray under the converter housing to receive the engine coolant. 

 

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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© 2005 Mitchell Repair Information Company, LLC.