Mark B.

We are contemplating buying a 1999 RX300 from a mechanic who is making necessary repairs. He is trying to figure out why the Check Engine light is on, throwing the O2 sensor error code, despite his having replaced both O2 sensors with Denso ones, and the plugs while he had the manifold off. Also replaced the alternator with a re-manufactured one. The car has 139K miles, and the tranny seems to be shifting properly. I suppose that either it is one of the "good" ones, or has been replaced previously. Anyway, guess I ought to keep $4K on reserve for a tranny if necessary. What about having a rebuild kit put in, instead of buying a new tranny? Are there any ways to flash the tranny firmware so as to make it more durable or otherwise improve it? Are there any brands of trannys available for this car that are better than others or better than OEM? thanks, guys.