Thanks for the reply. Since this tool is new to me, I didn't recheck the settings. It turns out the tool was set to Europe and when I chose Lexus it only said 433Mhz, not 315 like her car has. DOH moment and all is good. I was able to verify all 5 sensors are good and all are reporting pressure within 2 PSI of door tag. Light is still on and after driving for required number of miles at 19MPH or better its still the same. I have told her to contact CarMax as this has been an issue since purchase. She broke her foot and wasn't able to take it in for a while and since I have been working on autos for 40+ years, this tool was a welcome addition to my tool box.