HO2S Heater Inspection

Remove the battery cover. (See BATTERY REMOVAL/INSTALLATION .)
Disconnect the negative battery cable. (See BATTERY REMOVAL/INSTALLATION .)
Disconnect the HO2S connector.
Measure the resistance between HO2S terminals C and D.

Fig 1: Identifying HO2S Connector Terminals C And D
Courtesy of MAZDA MOTORS CORP.
- If not as specified, replace the HO2S. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION .)
  HO2S heater resistance
- 2-50 ohms [normal temperature]