I have a 1999 lexus GS 300 with 106,750 miles and just recently got the check engine light with the p0125 error code. Ive been told this is most likely an 02 sensor. Before i bring it to the mechanic i figured i'd get some insight from the Club Lexus community. What can i expect to pay for this error? is it a common error code on these vehicles?

 

Really, the best thing to do is do it yourself, a shop can easily charge you close to $90 just for the part, + labor.
Honestly, if you don't mind it, and the 02 that is bad is downstream (after the catalytic converter) then its not affecting performance at all. Just throws a CEL. If its up stream (which I think it is, then it could affect performance) Ive had my Check Engine Light on for a bad 02 (Sensor 2, Bank 1 downstream) and i've been ignoring it for a good 6 months. But if you really need it done, you can do it yourself, just get a spark plug socket, remove the heated 02 sensor plug the new one in, tighten it in, and the CEL should reset itself automatically after a while, or just disconnect the battery. I recommend the OEM Denso 02 sensors. There are write up on replacing them on the forum, but its straight forward really.

 

i have one o2 sensor off a working exhaust manifold, 25 shipped if you need.

came off a low mileage car.