Honda Error Code P0138: How to Fix It

Q: What causes Honda P0138 error code?

P0138 is typically caused by a faulty downstream oxygen sensor, damaged sensor wiring, exhaust leaks near the sensor, or rarely, a malfunctioning ECM. The most common cause is sensor failure due to age or contamination.

Q: Can I drive my Honda with P0138 code?

You can drive short distances, but prolonged driving isn't recommended. P0138 can affect fuel economy and emissions, and may cause damage to the catalytic converter if left untreated. Address the issue promptly.

Q: How much does it cost to fix P0138 on a Honda?

DIY repair costs $50-150 for a replacement oxygen sensor. Professional repair typically costs $200-400 including labor. Costs vary by Honda model and local labor rates.

Q: How long do Honda oxygen sensors last?

Honda oxygen sensors typically last 60,000-100,000 miles. Downstream sensors often last longer than upstream sensors because they're exposed to cleaner exhaust gases after the catalytic converter.

Q: Will P0138 cause my Honda to fail emissions testing?

Yes, P0138 will likely cause your Honda to fail emissions testing because it indicates the emissions monitoring system isn't functioning properly. The code must be resolved and the readiness monitors must complete before testing.

Abstract

Honda error code P0138 indicates that the downstream oxygen sensor (Bank 1, Sensor 2) is reading a consistently high voltage signal. This sensor monitors exhaust gases after the catalytic converter and helps your engine's computer optimize fuel mixture and emissions control.