Resistance Inspection (HO2S heater)

WARNING: This page is about a different car, the 2009 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

Disconnect the HO2S connector.
Measure the resistance between HO2S terminals C and A.
- If it is not within the specification, replace the HO2S. See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [MZI-3.7] .
  HO2S heater resistance
  
  2-50 ohms
  
  Fig 1: Identifying HO2S Connector
  Courtesy of MAZDA MOTORS CORP.