Operation CHARM: Car repair manuals for everyone.

HO2S Bank 1 Sen. 1/Bank 2. Sen. 1

Scan Tool Displays READY or NOT READY. Indicates the status of the fuel control exhaust oxygen sensor. The scan tool will indicate that the exhaust oxygen sensors are ready when the PCM detects a fluctuating HO2S voltage sufficient to allow closed loop operation. This will not occur unless the exhaust oxygen sensors are warmed up.