Master System Warning Light On

@thepinktaco is correct. The message only stays on the status screen briefly after starting the engine. I don't know why they decided to program it to stay on - previously, for 450 of the last 500 miles before scheduled service, the light flashed at start-up and eventually went out, then stay lit for the remaining 50 miles. This change is designed to be totally annoying, and get you to come into the dealer for service. Apparently, too many owners were ignoring it.

 

Breakdown on the highway- Crank Case Sensor issue. I had the Master Warning light come on at 4200 miles on my 2016. Brought it in and dealer said it must be the maintenance.
Why would Toyota have a specific light just for Maintenance then dealer determine the Master Warning light comes on instead and serves the same purpose- IT DOES NOT read on. Dealer reset light and did not plug into computer fro diagnostic at 4,200. at about 5,300 miles my truck shut down on the highway, towed to another dealer and explained how the Master Warning light was on and was reset by another dealer.

They inspected and found the Crank Case Sensor to be failing and Toyota has developed a new part because of this issue. The dealer that services this claimed these are tow distinct and different lights.

Maint. light is maintenance related. Master Warning light is when the you know what hits the fan. I think my breakdown could have been avoided if the 1st dealer ran a diagnostic.