TLDR: Can ScanGauge II inadvertently alter the TPMS sensor registration in the TPMS ECU? Full story: I've observed a potentially interesting interaction/problem regarding SG-II and TPMS. I've had a ScanGauge-II plugged into my 2010 Prius since Aug 2010. Initially, my TPMS light would only come on for extended trips (post tire replacement), however on my last Prius Expert trip to SoCal, the light came on and stayed on. I did remove my ScanGauge to place into other Prius vehicles during that trip (Prius v, specifically). I took the car in last week to have the light addressed. Initially, the Toyota tech at my dealer identified that one of my 4 sensors was damaged during my last tire install and replaced it, which we thought corrected the condition. The light stayed off for about 25 miles, then reappeared. I hadn't changed any XGauges during the entire time. I took it in a 2nd time where they kept the car most of the day. The tech took another look and found that the last few characters of the TMPS sensor IDs had been modified in the ECU, so they re-initialized the system again, inputting the correct numbers. All was well until they plugged in my ScanGauge II again. As soon as they did, the TPMS light came back on. They plugged their TechStream in, and observed 2 of the 4 wheel IDs had the last few digits modified again. Still having the old numbers on the screen, they corrected the last few numbers. They asked me to keep the ScanGauge off for at least 72 hours. I intend to give it a few weeks to see if the numbers drift again (which could point to a failing ECU instead of the SG-II). At the time of the test, I had the following Xgauges setup for display: Engine RPM (Passive TXD 01CC) Friction Brake Sensor (TXD 07B02107) HV Battery SoC (TXD 07E2015B) HV Battery Amp draw (TXD 07E2218A) My ScanGauge was set for fast polling (vs normal or slow). In the past when this light came on, I've also had other XGauges displayed - including AC draw, Fuel GPH, HV battery temp and Engine coolant temp, along with some other braking stats displayed. The SG-II had firmware 3.17mb, though I sent it off yesterday to Linear Logic for a firmware upgrade (before I was able to talk to the Toyota tech today for "root cause"). Interestingly enough, he claims that he's seen this on 1-2 other cars as well. I'm curious - has anyone else seen this? Are the TPMS initialization "codes" known or obtainable? Are they anywhere "near" the TXDs we use? I'm grateful that I wasn't charged for this effort (extended warranty), but concerned about plugging the unit back in to trigger the condition again w/o understanding if specific TXDs may be inadvertently triggering this, or if I should be concerned that my unit (or the cable) is failing and/or sending bad data. I'll probably end up calling Linear Logic on this as well to see if they have any thoughts on it, but wanted to poll the folks here in case this was something already observed.