What usually causes it
- A failed oxygen sensor
- A wire shorted to power or a damaged plug
- An engine running too rich, with extra fuel in the exhaust
- Fuel or coolant contamination of the sensor
P0138Starts at: OK to drive, fix when convenient
Oxygen sensor reads high (bank 1, sensor 2)
The oxygen sensor checks the exhaust. Sensor 2 sits after the catalytic converter (the exhaust part that cleans the fumes) on the side of the engine with cylinder 1, and its signal stays high.
Check this first
Look at the wires going to the sensor for melted or damaged spots once the exhaust is cool.
What to watch for
- A strong smell of gas or black smoke
- Poor gas mileage
- A flashing check engine light, which means a bad misfire
Can I keep driving?
We rate P0138 as OK to drive, fix when convenient, as a starting point. Keep an eye on the signs below. If the light starts flashing, stop driving soon.
Quick answers about P0138
What does P0138 mean?
Oxygen sensor reads high (bank 1, sensor 2). The oxygen sensor checks the exhaust. Sensor 2 sits after the catalytic converter (the exhaust part that cleans the fumes) on the side of the engine with cylinder 1, and its signal stays high.
Can I keep driving with P0138?
We rate P0138 as OK to drive, fix when convenient, as a starting point. Keep an eye on the signs below. If the light starts flashing, stop driving soon.
What usually causes P0138?
The most common causes, in order: A failed oxygen sensor; A wire shorted to power or a damaged plug; An engine running too rich, with extra fuel in the exhaust; Fuel or coolant contamination of the sensor.
Estimates only. A mechanic should confirm. The same code can mean slightly different things on different cars; the app explains it for your exact year, make, model and mileage.