ABS Control Unit
ABS stands for anti-lock braking systems. It is used to keep the wheels from locking up, which could cause your car to skid. The ABS will help stop your car as quickly as possible. The ABS control unit is the brain of the whole operation. It measures the brake pressure and then uses the speed of the wheel as an indicator of how much brake pressure is needed to apply or release.
When there is something wrong with the ABS control unit, there will be a yellow or orange “ABS” light on the dash to warn you. When this happens, you should have your car checked by a mechanic. The bad news is that the ABS control unit is one of the most labor-intensive and expensive car parts to repair. So once you see that ABS warning light on your dash, make sure you have some cash on you too.
Muffler
Engines are very loud and the muffler turns down the noise level to a tolerable level. A good muffler allows you to cruise down the street without having to announce your presence by making a racket of noise.
The muffler can get damaged because of rust, poor sealing, or bad welding. When this happens, your muffler can get holes that would let all the noise out. To regain your peaceful silence, you will have to replace it.