,We've all seen it at one time or another, stupid, annoying, finicky system that takes the fun out of driving (or saves your life, in some cases, but not usually)
There are a myriad of things that can cause this, but the most common by far, is the steering position sensor, located at the base of the steering column. just before the first disconnection point of the steering linkage. There is a 2 likely possibilities for this unit, it's either bad, or needs to be re-aligned. I've had both issues.
First thing you need to do is get a code read on the error, O'Reillys does it for free and has the correct scanner to give you the code "C0455" Once you confirm the code is for the steering sensor, then you can continue with these steps
If it comes on right when you start up, the sps is junk, replace (may need alignment, continue on) if it comes on after driving, go to a large enough parking lot, restart the car, turn the wheel a half turn left, drive to 10 mph, did it come on? Try again (after restart ) half turn to right, test. Repeat test with a full turn in either direction. Is there any position where it does not come on? If so, THAT is the position that it thinks the wheel is straight. The sps only mounts 2 different ways due to the oval opening, hence the half or full turn tests If you find a position where it stays off (electronically "straight"), leave the steering wheel in that exact position, (strap it with a bungee, never spin the wheel! You'll break the clock spring!) Disconnect the steering under the dash, remove the sps, reconnect the steering, turn the wheel straight, re-strap the wheel, disconnect the steering, reinstall the sps (do not spin it, be careful), reconnect the steering and test, should be good now! I have done this on 2 TrailBlazers with success. Good luck!
If no position will keep it from malfunctioning at 10 mph, replace, then reattempt alignment.
Steering sensor is item 3, if you look at the shaft it slides onto, it can only go 2 ways, but if you twist it before installing, it will be out of alignment.