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HO2S Heater Inspection

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.
  1. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
  2. Lift up the vehicle.
  3. Remove the floor under cover. (With floor under cover) (See FLOOR UNDER COVER REMOVAL/INSTALLATION .)
  4. Remove the insulator and brace bar. (2WD) (See EXHAUST SYSTEM REMOVAL/INSTALLATION .)
  5. Disconnect the HO2S connector.
  6. Measure the resistance between HO2S terminals C and D.

    HO2S heater resistance 

    2-50 ohms [normal temperature] 

    Fig 1: Identifying HO2S Connector Pins
    G09758753Courtesy of MAZDA MOTORS CORP.