Question 1

Do you use OEM or aftermarket keys on Lincoln vehicles?

Accepted Answer

We use blanks built to OEM spec, meaning the factory FCC ID, the correct transponder chip for the year and platform, and the right frequency. On the 2009 MKS specifically, the smart key architecture shares its roots with Ford's platform from that generation, so Ford-origin blanks that match the spec work identically to Lincoln-branded ones. The only real difference is usually the badge on the housing. What matters is that the chip type and frequency match what the vehicle's immobilizer expects, and that the shell is quality enough to hold up to daily use. We don't use the brittle aftermarket housings that owners on forums complain about cracking within a few months.

Question 2

How long will a replacement key last on a 2009 MKS?

Accepted Answer

The programming itself doesn't wear out. A well-made key registered to this car should keep working as long as the fob is intact and the battery gets swapped when it weakens. The CR2032 in these typically runs a couple of years under normal use. What fails first on most fobs is the housing, specifically the buttons, which wear down and eventually stop making clean contact. Quality shells hold up. Cheap aftermarket ones don't. If you keep the fob out of water and don't use it as a bottle opener, there's no reason a properly built replacement shouldn't last you several years without any electronics issues.

Question 3

What if my new key stops working a few weeks after you program it?

Accepted Answer

Call me. Everything I program is covered under warranty.

That said, when a newly programmed key stops working on these, the car is usually the reason, not the key. The vehicle security system can drop a learned key ID if there's an underlying module issue or a low battery in the vehicle itself triggering a reset. A key-not-detected warning that appears on a freshly programmed fob is worth diagnosing at the vehicle level before assuming the key is bad. I troubleshoot the actual cause rather than just handing you another fob and hoping.

Question 4

I found a used 2009 MKS fob online for cheap. Can you just program that one instead of buying a new key?

Accepted Answer

Sometimes, but it's a gamble worth understanding before you buy. A used smart key for this vehicle has a history. If it was previously registered to another car, it needs to be erased and re-enrolled to yours, which requires the same diagnostic process as a new key. The programming cost doesn't change just because the fob is used. The real risk is the condition of the used unit. Forum threads on these MKS fobs are full of buyers who got a fob with a cracked internal board, corroded battery contacts, or a worn-out button pad that looked fine in photos. If the used fob has a problem inside, you've paid for a part and still need a new one. New blanks built to spec are not dramatically more expensive, and you know what you're getting. If you already have a used fob in hand and want to try it, bring it along when you call me and we'll go from there.

Question 5

Only one door handle is detecting the key on approach. The other side acts like the fob isn't there. Is this a key problem?

Accepted Answer

Probably not. If the vehicle recognizes the fob for starting and the other handle works normally, the key is doing its job. Uneven door handle detection on this generation of Lincoln smart key systems is typically a door-side issue, either the handle antenna or the wiring to that door. Owners on MKS forums report this happening on the driver side after weatherstripping work or door panel removal where the antenna connection got disturbed. Wipe the handle area clean and retest. If it stays isolated to one handle, the key isn't the problem.

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