# Code: P0138 O2s

**URL:** <https://community.cartalk.com/t/code-p0138-o2s/177547>\
**Category:** General Discussion\
**Tags:** toyota, yaris\
**Created:** [June 18, 2021, 8:05pm UTC](https://community.cartalk.com/t/code-p0138-o2s/177547 "2021-06-18T20:05:52Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![mggirl1955](https://avatars.discourse-cdn.com/v4/letter/m/22d042/32.png) [@mggirl1955](https://community.cartalk.com/u/mggirl1955)\
**Post date:** [June 18, 2021, 8:05pm UTC](https://community.cartalk.com/t/code-p0138-o2s/177547/1 "2021-06-18T20:05:52Z")

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I have a 2013 Toyota Yaris with about 50,000 miles on it. My check engine light keeps coming on. It’s been doing this for almost a year. I borrowed a car code reader diagnostic tool and it gave me this reading: CODE: P0138 O2s ckt high volts. It was suggested that I add Techron complete fuel system cleaner to a tank of gas and drive the car on the highway for 30 - 60 miles. This worked for a little while, and I was able to get an inspection sticker, but the check engine light eventually came back on. I tried using the fuel system cleaner again, and it worked, but now the light has come back on. A friend told me not to worry about it unless the car started sounding funny. I’m just worried that if I don’t have this taken care of, I might do more harm to my car in the long run. Could you give me your opinion on this problem. Thanks for your help.

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**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\
**Post date:** [June 18, 2021, 9:07pm UTC](https://community.cartalk.com/t/code-p0138-o2s/177547/2 "2021-06-18T21:07:13Z")

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Get it fixed correctly. The emissions system has an 8 year, 80K mile warranty on it so I think this should be covered by Toyota. You will probably have to pay a diagnostic fee but the rest should be covered.

Or you could just replace the O2 sensor They are cheap and easy to replace.

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**Author:** ![mggirl1955](https://avatars.discourse-cdn.com/v4/letter/m/22d042/32.png) [@mggirl1955](https://community.cartalk.com/u/mggirl1955)\
**Post date:** [June 30, 2021, 2:29pm UTC](https://community.cartalk.com/t/code-p0138-o2s/177547/3 "2021-06-30T14:29:32Z")

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Mustangman, thank you for your reply.