Heated Oxygen Sensor (Ho2S) Removal/Installation

WARNING:

• A hot engine and exhaust system can cause severe burns. Turn off the engine and wait until they are cool before removing the exhaust system.

CAUTION:

• Do not allow flammable objects such as the taping for bundling a wiring harness to come into contact with the exhaust manifold and silencer.

NOTE:

• If penetrant lubricating spray penetrates the airflow hole of the HO2S, it could cause interference with the HO2S function.
• When removing the HO2S, wrap a rag around the lower position so that penetrant lubricating spray does not get sprayed into the airflow hole.

Fig 1: Wrapping Rag Around HO2S Sensor

Courtesy of MAZDA

Fig 2: Identifying HO2S Sensor, Connector And Clips

Courtesy of MAZDA

1. Disconnect the negative battery cable. (Refer to NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
2. Lift up the vehicle.
3. Remove the floor under cover. (Refer to FLOOR UNDER COVER REMOVAL/INSTALLATION .)
4. Disconnect the HO2S connector.
5. Remove the insulator and brace bar. (Refer to EXHAUST SYSTEM REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
6. Remove the clip C from the body.
   Fig 3: Identifying Clip C

   Courtesy of MAZDA
7. Remove the clip A and clip B from the catalytic converter.
   Fig 4: Identifying Clip A, Clip B And Nuts With Torque Specifications

   Courtesy of MAZDA
8. Remove the HO2S using the SST. 
   Fig 5: Removing HO2S Using SST

   Courtesy of MAZDA
9. Install in the reverse order of removal.