engine codes p0136 and p0138.too much volts heat side of o2 sensor? on 2000 Honda Civic

light went on, cleared code went back on next day,got above codes.took to shop said o2 sensor1 gettn too many volts.light when back off stayd off for 10 days.back 2 shop tested wiring with flowchaart but car kept gong back 2 normal range.suspect main computer does this sound right way 2 diagnose this or nd to go to dealer b4 shelln out computer money?

Asked by for the 2000 Honda Civic