P0138: O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)
Short answer: P0138 means “O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)”. It is a standard OBD-II code, so the basic meaning is the same on every car. Below is what it means on each of the 6 cars we cover, with a link to the full page for each car.
Standard OBD-II code Same meaning on all cars (SAE J2012).
P0138 on each car
| Car | Meaning on this car | Confidence |
|---|---|---|
| Toyota Passo (1st gen) | Oxygen Sensor High Voltage (B1S2) | low |
| Toyota Corolla (11th gen, E170) | O2 Sensor Circuit High Voltage (Bank 1 Sensor 2) | medium |
| Toyota Corolla (10th gen, E140) | O2 Sensor Circuit High Voltage (Bank 1 Sensor 2) | medium |
| Honda City (5th gen, GM2) | O2 Sensor Circuit High Voltage (Bank 1 Sensor 2) | medium |
| Honda Civic (10th gen, FC) | O2 Sensor Circuit High Voltage (Bank 1 Sensor 2) | medium |
| Suzuki Wagon R (Pakistan, K10B) | O2 Sensor Circuit High Voltage (Bank 1 Sensor 2) | medium |
Symptoms
- Check engine light on
- Fuel pressure can over rich the system
Likely causes
- Faulty O2 sensor
- Short to battery voltage in O2 sensor signal circuit
- High fuel pressure (not as likely)
What to check, in order
- Read the code and live data with an OBD-II scanner
- Look for exhaust or vacuum leaks and check the wiring of the sensor or valve
- Test the part before replacing it
- Fix the cause, clear the code and test-drive
Causes and checks above are the general meaning. The exact test steps and values differ by car: open your car’s page.