The sentence in italics is a conditional sentence, but it's faulty. If the writer had intended to write in the "third conditional" the sentence should have been written thus: If you had lived in Petaling Jaya, you would probably have heard of it. However, we use the third conditional to express regrets for something that happened or didn't happen. Here's an example: If I hadn't missed the bus, I would have arrived at the office on time. It's quite obvious that the third conditional is not appropriate in this context.
The writer should have expressed his idea in the "first conditional": If you live in Petaling Jaya, you will/would probably know this. This sentence is possible as it expresses the idea that if the condition is fulfilled, the result is likely to happen. The use of would makes the writer's assertion more tentative.