Pulsating Brakes

Hi,

I have been experience a pulsating sensation from my front brakes for quite some time now. I’m going to work on the issue but need to know if that pulsation is from the rotors, the brakes or a combination of both. I think the rotors are warped but wanted to verify before I work on the vehicle.

2001 Pontiac Grand Prix GT 3.8

Thanks

My guess is warped rotors, Any abs codes?

The ABS light recently came on but is throwing a code for the speed sensor on the drivers side rear.

Maybe it is just dirty? What was the actual code?

Speed Sensor LR