Coils don't have any moving parts, how do they crack? First of all, VW and Audi don't make their own coils and coil packs. They have them made for them by major manufacturers like Bosch, Temic, Beru, etc. While there are no moving parts, the coils do wear. Heat, time in use (mileage), and the quality of the coil pack have everything to do with how long a coil pack can survive.

4cyl coil pack installed. See a problem?

Coil pack removed for inspection. One spark plug wire was hiding a chipped wire nipple. But wait! There's more!

Look! A crack in the side! This one has to go in the recycle bin.

Attention to detail is vital to a proper inspection. A mechanic who's too lazy to remove the coil and fully check it out would cost this customer some serious money. How? Here's how. A cracked coil pack can cause a skip, especially in wet weather or damp weather. A skip is where one cylinder of the engine isn't firing. When one cylinder isn't firing, the air and fuel goes through the engine without burning, and into the catalytic converter. Converters are dumb. They can't throttle themselves. They just burn harmful things, converting them into harmless gases. So, if you have one cylinder not firing, raw fuel and air will enter the converter and the converter will burn that charge, even to the point where it melts down inside. The catalytic converter costs big bucks. It's made of stainless steel, platinum, palladium, and rodium. All of these materials are pricey. Some are worth more than gold. It only takes a few short minutes of driving with a skip to slag a catalytic converter. Once the converter stops working the check engine light will come on and nag you until you replace it. If the converter slags completely, the exhaust can completely clog and the car won't be able to make enough power to drive down the road. Kind of like a potato in your tailpipe. Since 1996 cars have a check engine light that flashes on and off when the engine is skipping, or misfiring. Pull the car over if the check engine light flashes. It's far cheaper to let us come tow the car in and fix ignition problems than to drive it home and have us fix the ignition problem AND install a new cat.