In the general sense, do oxygen sensors wear out, and specifically could I see improved mileage if I replace my upstream sensors.
I’m driving a 2000 GMC 1500, 5.3l with about 150,000 miles. Combined mileage is in the 15-16mpg range, and the car hasn’t pulled any trouble codes apart from a P0172 (Fuel Trim System Rich Bank 1) that was due to a weak fuel pump. The pump has been replaced, with a noticeable improvement in starting and possibly a perceived improvement in throttle response.
I’d like to replace these if I will see a return in mileage. I don’t want to waste money though, and oxygen sensors are not listed in the GMC maintenance schedule.