OBD-II code · Powertrain (generic)
P0139 O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)
The ECU detects that the downstream oxygen sensor on bank 1 reports an abnormally high voltage signal, suggesting a persistently rich exhaust condition past the catalyst, a shorted sensor, or wiring shorted to a voltage source.
Is it safe to drive with P0139?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyEngine running rich (leaking injector, high fuel pressure)
- PossibleSensor signal wire shorted to voltage
- PossibleDownstream O2 sensor failed
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–1.5 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Oxygen Sensor B1s2, Oxygen Sensor Wiring, Catalytic Converter Bank1
Related codes
- P0145O2 Sensor Circuit High Voltage (Bank 1 Sensor 3)
- P0153O2 Sensor Circuit High Voltage (Bank 2 Sensor 1)
- P0159O2 Sensor Circuit High Voltage (Bank 2 Sensor 2)
- P0165O2 Sensor Circuit High Voltage (Bank 2 Sensor 3)
- P0136O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)
- P0137O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)
- P0138O2 Sensor Circuit High Voltage (Bank 1, Sensor 2)
- P013AO2 Sensor Slow Response - Rich to Lean Bank 1 Sensor 2
- P013BO2 Sensor Slow Response - Lean to Rich Bank 1 Sensor 2
- P013CO2 Sensor Slow Response - Rich to Lean Bank 2 Sensor 2
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.