O2 Sensor Circuit High Voltage (Bank 1, Sensor 2)
Powertrain Code · Medium
What does P0138 mean?
High voltage from the downstream O2 sensor on bank 1.
System: O2 Sensor
P0138 is a powertrain diagnostic trouble code indicating o2 sensor circuit high voltage (bank 1, sensor 2). This code is classified as medium severity, which means: schedule service — affects performance or emissions. We have vehicle-specific diagnostic data for 12 models below. Select your vehicle for tailored causes, symptoms, and repair cost estimates.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your vehicle.
See causes, symptoms, and repair costs for P0138 on specific vehicles: