P0138
O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)
OBD-II
Oxygen sensors
What it means
Downstream O2 reads persistently high — contaminated sensor or a shorted signal wire.
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Check your car freeRelated codes
P0030
HO2S Heater Control Circuit (Bank 1 Sensor 1)
Oxygen sensorsLow
P0031
HO2S Heater Control Circuit Low (Bank 1 Sensor 1)
Oxygen sensorsLow
P0032
HO2S Heater Control Circuit High (Bank 1 Sensor 1)
Oxygen sensorsLow
P0036
HO2S Heater Control Circuit (Bank 1 Sensor 2)
Oxygen sensorsLow
P0037
HO2S Heater Control Circuit Low (Bank 1 Sensor 2)
Oxygen sensorsLow
P0038
HO2S Heater Control Circuit High (Bank 1 Sensor 2)
Oxygen sensorsLow
P0042
O2 Sensor Heater Control Circuit (Bank 1 Sensor 3)
Oxygen sensorsLow
P0043
O2 Sensor Heater Circuit Low (Bank 1 Sensor 3)
Oxygen sensorsLow
General reference only — what a code means can vary by make and model. Confirm with a qualified technician.