DTC P0138 - HO2S CIRCUIT HIGH VOLTAGE SENSOR 2 Oldsmobile Cutlass VI

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

Circuit Description

The Heated Oxygen Sensor 2 (HO2S 2), located rear of catalytic converter produces an output signal relative to oxygen storage capacity of catalytic converter. HO2S 2 signal is less active than signal produced by front oxygen sensor.

Conditions for setting this DTC are as follows

1. Engine coolant temperature is greater than 167°F (75°C).
2. Engine run time is greater than 25 seconds.
3. TP sensor angle is 5-40 percent.
4. Air/fuel ratio is 14.5:1-14.7:1.
5. Engine is in closed loop.
6. HO2S 2 voltage is greater than 999 mV for more than 2 minutes.