Never use a deadbolt that is operated by a key on both sides of the lock, commonly refered to as a double-sided deadbolt. These locks should be prohibited by law. I always ask customers who request them, “What is more valuable, your television or your life?”. In the case of a fire, these locks can lead to your death. One manufacturer does make such a lock that uses a key on the inside with a knob on the key. This lock also retains the inside key unless you use a key from the outside. The theory behind this is logical, but if anyone uses another point of entry and forgets to put the key back in, an extreme risk has been created.
Modern ignition locks have become more complex and this has led to increased failure occurrences. Ford Focus’s, Honda’s, Toyota’s, Chrysler and GM locks may experience failures due to many causes such as wear, poor design and small amounts of foreign debris being inadvertently inserted into the lock. Most failures result in the lock failing to operate with the proper key and require replacement or rebuilding.
Maintaining the use of the original key is extremely important. Most vehicles are now designed to use the same key for the ignition lock as well as other locks such as the trunk. When all keys are lost, a professional can obtain the original key code or use a door or trunk lock to generate a key. When locks using different keys are used to replace an existing ignition lock, a real problem is created, requiring the replacement of the lock when keys are lost. Locks that have failed should only be repaired by a professional automotive locksmith or a new car dealer that has the ability to code the new lock properly to match the original key. Many Asian auto makers only supply replacement locks that do not match the original keys. In this case it is very important to require the service provider have the new lock rekeyed to match the original key, by a competant automotive locksmith.
Most Honda, Toyota and other Asian vehicles are simpler to rebuild than replace do to the fact that easily rekeyed replacement locks are not available. Most Toyota failures occur from their use of split wafers, which I recommend be removed. Honda locks using a milled key instead of the older keys that can be cut on the same type of machine that cuts and duplicates common keys such as your house key, have split wafers that have been designed with a very fragile tip that is actuated by the key. These small tips, about the size of a large pin head can easily be broken off or deformed by a worn key or by forcing a key into a unlubricated lock.
Chrysler, Ford and G.M. locks that we use are produced by the same company that supplies the original manufacturer and we purchased them unkeyed so they can be matched to the original keys. Ford Focus locks had a severe design flaw and we replace those with a new lock utilizing a far stronger and reliable design. The same is true of some G.M. locks that were originally supplied by German or Asian companies, and they are replaced by an improved design lock.
Never use a replacement lock from an auto parts store. Only purchase a replacement lock from a professional automotive locksmith or new car dealer that can key the new lock to match the original key. I have encountered numerous aftermarket locks that have failed or the keys have been lost. Most of these locks are very inferior in material, design and security.
It is very important to use a professional automotive locksmith or new car dealer parts when replacing a lock. Not all locksmiths are competent to service vehicle locks. Vehicle locks and keys comprise the most complex devices that locksmiths service. Most commercial and residential locks are fairly easy to service but automotive lock servicing requires a very high knowledge of auto body service as well as steering column and interior panel removal. I have seen thousands of dollars in damage done by unskilled locksmiths and service techs that lacked the proper knowledge to service the locks.