Most people don't realize that car seats expire, but they do. Newer car seats have the expiration date listed on the shell, and you can always check your car seat's manual for the expiration date. Some seats expire in five years while others last as long as eight years. Each manufacturer is different. Regardless of that, once your child's car seat expires, it's time for a new one.
Also, this is a direct quote from my reference at the bottom...
"Parents should know that NHTSA instructs its techs and both Safe Kids and the Juvenile Product Manufacturers Association agree that no seat should be used for more than a period of 6 years from its date of manufacture"
They expire for three reasons...
1. Technology changes
2. Materials where down
3. The manufacturer may no longer manufacture replacement parts.
You can check the first reference for how to find your car seat's expiration date.
Another reason that you have to get a new car seat is if it has been in a moderate to severe wreck. It does not matter if the child was in the seat at the time or not. You must get a new one if the seat was in the car when the car was involved in an accident. You do not have to get a new one if it was only a minor wreck...
- The vehicle was able to be driven away from the crash site;
- The vehicle door nearest the safety seat was undamaged;
- There were no injuries to any of the vehicle occupants;
- The air bags (if present) did not deploy; AND
- There is no visible damage to the safety seat.
If ALL of these criteria are not met, then a new car seat is needed.