OBD-II Generic Error Code P0138: How to Fix It

Q: Can I drive with code P0138?

Short distances are possible, but it's not recommended. Driving can cause poor fuel economy and potentially damage the catalytic converter over time.

Q: What does 'Bank 1 Sensor 2' mean?

Bank 1 refers to the side of the engine containing cylinder #1. Sensor 2 is the downstream oxygen sensor located after the catalytic converter.

Q: Will replacing the O2 sensor fix code P0138?

Often yes, but first check for exhaust leaks and wiring issues. A faulty sensor is a common cause of this code.

Q: How much does it cost to fix P0138?

DIY replacement can cost $50-$150 for the sensor plus tools. Professional repair typically runs $150-$400 including labor.

Q: Can a bad catalytic converter cause P0138?

Yes, a clogged or failing catalytic converter can cause high voltage readings. But the code usually triggers a separate code for converter efficiency (e.g., P0420).

Abstract

Error code P0138 indicates that the oxygen sensor on Bank 1, Sensor 2 (downstream of the catalytic converter) is reporting a voltage higher than the normal range (above 1.0V). This typically signals a rich fuel condition, a faulty sensor, or an exhaust leak. Ignoring it can reduce fuel economy and damage the catalytic converter.