most likely one of two things (just went through this last week).
1. sensor has become gunk'd and funk'd - remove and clean (might fix) or for the same amount of time invested buy a new one less than $20.
2. time to replace wheel hub assembly (contains the "ring" that the sensor measures for data). I mention this because i just replaced the hub due to snapping off 2 studs. put it all back together and on test drive received similar code - my superchips translated code to "Left Rear Wheel At Implausible Distance." dash lit up like a christmas tree and after each start of the engine (going under 10mph) abs would engage and pedal would plunge 3/4 of the way to the floor. sure enough, closer inspection revealed that one way or another the "ring" had been dented in a smidgen. "careful" manipulation with a steel chisel and a 3pound sledge got it rounded out again. good to go.
On my second '06 Commander - first was a Dark Khaki 4.7, I'm now in a Black 5.7 w/ RC 2", 1.25" Spacers, Custom Spectre 4" Intake w/K&N cone filter, NGK G-Power Platinum plugs, Superchips (91+ Tune), 245/70/17 Kenda Klever MT's,