Drive with caution — fix soon.
This code means the computer detected a problem with the upstream oxygen sensor on bank 1, the sensor that measures exhaust oxygen to adjust the air-fuel mixture. It's commonly caused by a failing O2 sensor, wiring or connector problems, or sometimes an exhaust leak near the sensor. Replacing the oxygen sensor or repairing its wiring usually resolves it, and it's a common, manageable repair.
$150 – $500
Varies by vehicle and root cause.
Usually yes for the short term. The car remains drivable, but the fuel mixture may be slightly off, so fix it soon to protect fuel economy and avoid stressing the catalytic converter.
Typically $150 to $500. The oxygen sensor itself plus labor makes up most of the cost, while a simple wiring or connector repair can be cheaper.
It's moderate severity. It won't usually leave you stranded, but ignoring it long-term can worsen fuel economy and eventually damage the catalytic converter, which is a much costlier repair.
Bank 1 is the side of the engine with cylinder number 1, and Sensor 1 is the upstream oxygen sensor located before the catalytic converter. That sensor is the one this code is flagging.