A shower pan does not usually announce itself. There is no drip through the ceiling below until real damage has already happened. By the time you see a stain or soft spot in the room underneath, the water has been getting past the pan for a while. The good news is you can check for early signs yourself, and none of it requires opening a wall.
Start with the grout and caulk at the floor of the shower, especially where the floor meets the wall and where it meets the drain. Press on it with a fingertip. If it feels soft, cracked, or if you can see daylight through a gap, water is finding a way through there every time someone showers. That does not mean the pan itself has failed, but it means the barrier that protects the pan is compromised, and that is where most leaks start.
Next, look at the floor just outside the shower, and the ceiling or wall in the room below if the shower is on a second floor or over a finished space. A discolored spot on the ceiling, a soft place in the floor near the shower curb, or a musty smell in that area are all signs water is already getting through. Tile that has come loose, or grout lines that have darkened compared to the rest, can mean water is sitting under the tile rather than draining off it.
There is also a simple test you can run yourself. Plug the shower drain, fill the pan with an inch or two of water, and let it sit for about 24 hours. Mark the water line with tape before you start. If the level drops noticeably and the drain is sealed, water is escaping through the pan itself rather than the drain fitting. This will not tell you exactly where the failure is, but it tells you whether the pan is the problem or whether the issue is somewhere else, like the tile surround or a fitting.
If you have access to the plumbing below the shower, whether that is a basement, a crawl space, or an access panel, check the drain trap and the area around it after running the test. Any dampness there points to the drain assembly instead of the pan liner.
Here is the part that matters for your wallet. A cracked grout line or failed caulk joint is a cheap fix, often just a resealing job. A pan that is actually failing, meaning the waterproof membrane underneath the tile or the pan liner itself has a hole or a bad seam, is not something you patch from the top. The tile and mud bed have to come out to get at it. That is a real difference in cost, so it is worth doing the drain test before you assume the worst or assume the best.
One more thing worth checking, if the shower is old and was built with a traditional mud pan rather than a manufactured pan, the liner underneath has a lifespan too. If the shower is original to a house built decades ago and has never been redone, age alone is a reason to have someone look at it even if you have not seen visible signs yet.
If your test shows water loss, or if you are seeing any staining below the shower, do not wait on it. A pan leak that reaches the subfloor turns a bathroom repair into a framing repair, and that gets expensive fast.
If you want a second opinion on what you are seeing, give us a call and we can take a look before you decide what to do next.