The most common causes of car accidents in California are not paying attention, people doing distracted driving because they are on their cell phones and the few times a year when it actually rains, people don't know what to do. That causes a lot of hysteria on Southern California freeways when all of a sudden two or three raindrops fall out of the air.
California does have statutes of limitations that can kick you out of court and not allow you file a case if you have waited to long. Cases are different and so depending on your injury and how you were injured and who injured you. It is very important that you seek legal advice immediately to determine what the statute of limitations is.
Generally, in personal injury cases, it is two years from the date of the incident. If the defendant, potential defendant, is a municipality, a government agency, you have six months to file a proof of claim. But again this is a situation that you need to talk to an attorney as soon as possible to look at the specific facts of your case.