I don't think there's ever been a timeline determined as to when these start acting up. I had one go out on my 05 Limited @ 30K, but my SRT still has the original one @ almost 50K. I've read some have gone out around 15K and others never have the problem past 100K. If she's your daily driver I'd go ahead and get a back-up since they are cheap enough, and small enough to store onboard with the right tools to do the replacement, just in case you're out in the middle of nowhere!