Quick checklist
Check O2 sensor wiring, test sensor
OBD2 Codes
P0138 – O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)
O2 sensor voltage too high
Details
The downstream O2 sensor voltage is abnormally high.
Typical causesFaulty O2 sensor, wiring short
SymptomsCheck engine light
SeverityMedium
DIY checksCheck O2 sensor wiring, test sensor
ToolsOBD2 scanner
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FAQ
Common questions
What causes P0138?
Faulty O2 sensor, wiring short
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