Red Triangle with exclaimation point and LCD says "PROBLEM"

The triangle comes on momentary for the past week. It first occurred when I turned right at 20 mph. The next time was during a sweeping left turn. Off and on with turns left and right. the last few times it was longer in different situations and I could read the LCD display where is said "PROBLEM".
The local dealer said check brake fluid and open and close all doors. Since it is more frequent I called my mechanic and he thinks it could be door sensors that have built up junk. Anyone have similar senario and a fix. The dealership does not think it is a safety issue and without any lights on their analyzer could not pull any codes.

Can anyone offer some things to look for.

I have changed all fluids regularily and the car battery in 2010 (not hybrid battery). 2005 package 2 with 190000 miles.