Front HO2S Heater Resistance Inspection

Disconnect the front HO2S connector.
Measure the resistance between front HO2S terminals 2B and 2D.
- If not within the specification, replace the front HO2S. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION ).
  
  Fig 1: Identifying Front HO2S Connector Terminals
  Courtesy of MAZDA MOTORS CORP.
Front HO2S heater resistance 1-10 ohms