I have a 2000 Civic SiR (Si in the US). My driver's side door suddenly won't unlock anymore. When I disarm my alarm only the passenger side unlocks. I've tried to unlock from the inside but it won't budge. From the outside the key won't turn. Is something frozen or seized (it's cold as hell here right now) or is it something mechanical?

 

It's possible that some of the lock actuators have gotten wet and frozen solid, but Honda locks aren't exactly known to be the sturdiest on the market so mechanical failure is indeed a possibility. My advice is to pull off the door panel and take a look.

 

If in fact its just due to the weather, should it work if it gets a bit warmer? Took my car to Krown Rust control to get get that rust control stuff sprayed and they washed it right after. I'm thinkin it's weather-related but I could be wrong...