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.

Disconnect the negative battery cable. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .)
Lift up the vehicle.
Remove the floor under cover (LH). (AWD) (See FLOOR UNDER COVER REMOVAL/INSTALLATION .)
Remove the floor under cover. (2WD) (See FLOOR UNDER COVER REMOVAL/INSTALLATION .)
Remove the insulator and brace bar. (2WD) (See EXHAUST SYSTEM REMOVAL/INSTALLATION .)
Disconnect the HO2S connector.
Measure the resistance between HO2S terminals C and D.

Fig 1: HO2S Connector Terminals

Courtesy of MAZDA MOTORS CORP.

HO2S heater resistance

2-50 ohms [normal temperature]