ajswep

Hello. Our 2000 es300 shut down while we were driving up the road going about 35-40mph. No warning, engine simply shut off. We pulled into a lot and tried to start it with no luck. Tried several things dealing with the security system because we just had trouble with it a couple days ago. Nothing worked. It cranked but wouldn't turn over.
We got back home, got our obd2 code scanner, and went back to see if we would get any codes. We didn't. But while the obd2 was plugged in we tried to start it and wha-lah, it started right up. Like nothing ever happened. Drove it home with the obd2 plugged in the whole time. When we got back home it did the same thing. Would not start unless it (obd2) was plugged in. Also, once we got it home we also noticed that the engine temperature gauge was all the way past hot until we plugged the scanner in again. Then everything went back to normal.
Has anyone ever had this happen? Any insight would be helpful. Either electrical or security related is the closest we can figure.
Thank you.