I’ve been told that my 2001 GS300 (60k miles) needs a new 02 sensor in the exhaust system. Dealer’s quote was $300 to $400. Necessary? Mandatory? Good price?
Not necessary, but if it is bad and if you don’t fix it, the next part to go is the converter and they cost more than O? sensors.
I might add that you likely can save a few dollars by taking your car to a local independent mechanic. Dealers are no better (or worse) than independent mechanics, but they almost always change more, but offset that with a nice waiting area.
If the O2 sensor is bad it needs to be replaced. Either pay the dealer or find an independent mechanic, who may charge slightly less.