Q: Would a bad crankcase valve caused by a tune up on my audi a3?

Hi Lisa. Thanks for contacting us today. Having a tune-up would not likely cause damage to a rear crankshaft seal. This typically occurs over time and is due to common wear and tear. It’s a hit or miss type of issue, but can be damaged due to excessive heat or an overheating incident. If the PCV valve is causing poor engine performance, then I would have that replaced ASAP. Replacing the rear crankshaft seal can be rather expensive, so you might want to carefully think about the cost of repair vs. the cost of selling this vehicle and purchasing a newer vehicle. My general rule of thumb is; if any repair will cost you more than 50% of the current blue book value of your car, then it’s a good idea to replace the vehicle. I would get a total cost of repairing your vehicle from your mechanic first, then make a decision based on that cost and your budget.