While applying the brakes for the first time after start up at low speeds (less than 20mph) the antilock brakes kick in when not needed. For about 2-3 seconds, there is extremely reduced braking ability. After this initial time period, the whole antilock braking system shuts down and also turns off the traction control system. Once the shutdown has taken place, the car's braking system functions as if there was no antilock brakes on the vehicle. Took car to dealership which indicated that the wheel sensor was bad and could be replaced for $600. Also while driving on the interstate, noticed that the speedometer was stuck at 65mph, regardless of speed. When turned off, the vehicle still read 65mph. Was unable to determine proper speed. Noticed that the vehicle reset the speed 5mph lower each time the ignition switch was moved from off to on. Multiple cycles of turning the ignition switch on and off finally reset the speedometer to 0mph. Don't know if this is only a temporary fix for a problem that will probably get worse. Although not a serious issue, the tachometer does the same thing.

- Moravia, NY, USA

My 2004 Impala's ABS trouble light came on as did the "service traction system" light. The dealers diagnosis based upon ABS scanner codes was that the left rear wheel speed sensor had failed/shorted. GM's sealed wheel hub design on this vehicle meant that in order to replace the wheel speed sensor the entire hub had to be replaced. Since the vehicle has just over 40K miles and is out of warranty, my total cost was over $690 including parts, labor, and taxes. This is absurd and ridiculous. It is unacceptable for the consumer to have to experience this kind of outrageous cost simply to get a sensor replaced. If it were not for the necessity of replacing the entire hub, there is no way that this repair should even cost $100. As a mechanical engineer, I recognize poor design and poor logic when I see it, and this situation certainly falls under those categories. I am extremely dissatisfied that I had no choice but to pay this in order to restore operation of the ABS and traction systems. If this is standard GM design practice, I will definitely consider that a negative when purchasing my next vehicle.

- Milford, OH, USA