Pressure is good in all four tires, and the car rides fine. My valve block on the driver's rear is going bad. The suspension has dropped overnight twice in the last five days. I'm working to get the warranty company to authorize the repair. Is this related?

 

The Tire pressure sensor in you front left tire is bad most likely. This has nothing to do with the ABC suspension.

 

Thanks. As soon as I read your response, I had one of those "a-ha" moments. I couldn't figure out what "FL" was, but obviously it's front left. I checked the pressure again, and it showed 29 psi. I put some air in the tire, and the fault code is gone.

 

I had the same thing show up when one of my TPMS sensors went bad. One trip to the dealer and it was sorted.