check eng lite on 1997 Toyota Avalon

had a scsn said o2 sensor sensor 1 bank 1,replaced sensor about 2 wks ago,lite went off 2 days came back on. scan also said heater circuit malfuntion.

Asked by for the 1997 Toyota Avalon
2 answers
Check for vacuum leaks for starters. Exactly which sensor did you replace? Was it the front or the rear? Does the code give you any more information?
Bank one on that engine is the rear bank of cylinders ensure the correct sensor was replaced. Heater circuit failure is common on these cars.