I tried to set up this poll a few times with no luck, so this is my latest attempt. I have grouped similar codes together without text.
Many thanks to Bob2200 for suggesting this.
Keep in mind to those visiting the forum for the first time, the fact that we are listing these codes by no means suggests the RX300 is a problematic vehicle (far from it), but the fact that in this forum we have been able to fix many of these codes on our own (rather than having to spend vast sums) is a true testament to the fine legacy of this vehicle. This is by no means meant to be a scientific poll.
OBD2 code scanners are relatively inexpensive and work across a variety of vehicles (generally 1996 model vehicles and newer). This is my trusty Actron CP9125 that I purchased for under $100 USD. They pay for themselves.
Amazon.com and better yet ebay are inexpensive places to find these scanners for much less than sold at auto parts stores. Many advanced scanners for under $100 USD can access information such as A/F sensor readings, coolant temperature, air intake temperature. In addition, if you have laptop there are many programs (with purchase of applicable hardware) that can connnect the laptop to your vehicle to enable the greatest amount of information to be displayed.
I recommend if you also have a 2005 or later model year vehicle (though there are some 2003-04 vehicles this will apply to) in addition to your RX300 to get a scanner that has the CAN protocol in order to work with those newer vehicles. An OBD2 scanner with or without CAN will still be able to scan your RX300. However, I highly recommend to pay the slight extra $$$ to get a CAN OBD2 scanner to increase its usefulness for all vehicles you may own. One other note, most vehicles before 1996, used OBDI, which is not compatible with an OBDII scanner.
All vehicles sold in the US effective the 2008 model year use CAN.
Most annoying code I ever had was VSC. I learned after some research that as long as any CEL code was active, VSC would refuse to operate (bastard). After spending a few months clearing dirty ABS wheel sensors and oxygen sensor codes, VSC still refused to go out. So I did the ZPC, zero-point calibration. I was a little skeptical that doing the few little steps, including shorting a few terminals would work, but low and behold, VSC LIGHT IS GONE!!
Other scary code situation was after I replaced ECU, having just been reflashed. I forgot to plug in one harness set and my car really did not like me, wouldn't shift right, A/C was blinking. Scared the crap out of me. After doing a little research, many people pointed to the ECU. Took only minutes to see I missed a harness. Thank heavens.
I currently am "borrowing" my dad's AutoTap which I use with my laptop to read and clear codes on the car. I heart OBD2.
I decided to buy one of the Actron CP9125 ( ebay -25 bucks). Then wondering about CAN option. Can someone point a good one that I should buy to explore codes on my Lexus RX300 1999 - running great at 185K miles on it.