Found this online. "Pennsylvania is a diminished value state, which means you may be entitled to the diminished value of your vehicle after an auto accident. The statute of limitation on diminished value claims in Pennsylvania is 2 years, and Pennsylvania does not have uninsured motorist coverage for diminished value."
Caveat: I am not licensed to practice in Pennsylvania.
Diminished value can be proven through expert testimony. You need to weigh the cost of litigating versus the actual diminished value before going forward. Make the insurance claim for it and see what they do.