Civic EX Sedan L4-1668cc 1.7L SOHC (VTEC) MFI (2001)
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Oxygen Sensor: Description and Operation
Secondary Heated Oxygen Sensor (Secondary HO2S)
Secondary Heated Oxygen Sensor (Secondary HO2S)
The secondary HO2S detects the oxygen content in the exhaust gas downstream of the TWC and sends signals to the ECM/PCM which checks the
efficiency of the TWC. To stabilize its output, the sensor has an internal heater. The secondary HO2S is installed in the TWC.
