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.
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.
Mustangman, thank you for your reply.