DTC P0140 - HO2S INSUFFICIENT ACTIVITY SENSOR 2 Pontiac Firebird IV

Note. For circuit reference, see the appropriate WIRING DIAGRAMS article. For connector and terminal identification, see CONNECTOR IDENTIFICATION .

Circuit Description

Heated Oxygen Sensor (HO2S) 2 refers to bank 1 sensor 2. Three-Way Catalyst (TWC) system is used to control emissions. PCM uses signal from Heated Oxygen Sensor (HO2S) behind TWC to read efficiency of TWC. PCM will set DTC P0140 if TWC oxygen storage capacity is less than a predetermined threshold.

Conditions required to set DTC are

1. No ECT, IAT, MAF, MAP or TP sensor DTCs set.
2. No EVAP system DTC set.
3. No fuel injector circuit, fuel trim, misfire or transaxle DTCs set.
4. Closed loop commanded air/fuel ratio is 14.5-14.8:1.
5. Engine run time greater than 200 seconds.
6. HO2S 2 voltage stays 0.425-0.474 volt for 50 seconds.