Lemon Law:
On purchasing a vehicle, a warranty period is fixed. If your vehicle have some specified defects and you have tried to fix it more than a reasonable no. of times (App. 4) within warranty period, Then your vehicle can be declared as lemon. Various states have different policies against lemon vehicles.
Note That:
1) In some states, you can simply make a complaint and find warranty advantage while in some states; you need to hire an attorney.
2) In case an attorney is needed, some states allows for refund of lawyer fee by loosing side.
3) Some states law also allows for leased vehicle to be treated as "Lemon vehicle" within warranty period if defect is found.
4) Keep a record of every repair, and save it in a document style. This will help you legally.
Since Lemon laws are different in each state, we will see only California Lemon law. In Most of the cases, you need to hire a attorney against lemon car manufacturer. Even if your car not be declared as a "lemon car" (Or other vehicle), there are a number of law which can protect you. So you can at least get refund of vehicle + attorney fee.
if a manufacturer or its representative can not repair a vehicle under express warranty after a fixed number of attempts, the manufacturer must promptly replace or repurchase it under consumer warranty act. Also vehicle should belong to California for family, business or personal use and Warranty period duration is company warranty period + time limit for taking a legal action.
If a car is sold then new buyer also have advantage of remaining warranty period but Car door should have a sticker named as "Lemon".

Lemon Law Rights :
A) If your car have a defect then Write to manufacturer.
B) If your manufacturers have a number, even then write a letter for legal reasons.
C) You can hire an attorney for manufacturer's arbitration program.
D) Read manufacturer's arbitration program rules to understand process.
E) Even if you loose in arbitration, remember that there is a higher chance that you can win in court.

There are special law under Warranty Act—Civil Code section 1793.22 (b) which can help you to determine about sufficient time limit in which, manufacturer was unable to repair your vehicle. These are:
A) If for the same problem you have taken your vehicle to manufacturer four or more times or your vehicle was a cause of serious injury or death.
B) The four repair attempts or 30 days out of service within first 18 months that you own your car or first 18,000 miles, whichever happens first (As of January 2000).
C) The problems are covered by the warranty and substantially impair the use, value or safety of the vehicle.
D) You must directly notify the manufacturer about the problem according to law.

If seller can prove that you have not handled the car carefully then he can even claim for attorney fee.

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