When replacing a lost, broken or damaged car key, you’ll often see terms like OEM, aftermarket and refurbished, but what do they actually mean? The choice you make can significantly affect reliability, compatibility and long term cost. In this post, we break down what each term stands for, their advantages and trade offs and how to decide which type of key best suits your car and circumstances.
What is an OEM key?
An OEM key, short for Original Equipment Manufacturer, is a key produced by the same manufacturer that supplied the original key when your vehicle was built.
Because OEM keys are designed to the factory’s exact specifications, they offer the highest level of compatibility with your car’s immobiliser, central locking, remote locking and electronic systems. Their housing, buttons, transponder chips if fitted and frequency match the original configuration, which means you rarely encounter programming errors or signal issues.
They are built to high quality standards and often include features such as waterproofing, robust casings and durable components, all of which contribute to long term reliability.
The downside is cost and availability. Because OEM keys come from official or authorised supply channels, they tend to be more expensive. For some makes and models, especially premium or more complex vehicles, they may need to be ordered specially, which can add waiting time.
What are aftermarket keys?
Aftermarket keys are produced by third party manufacturers rather than the original car maker. They are designed to function like OEM keys, but they are not made by the car’s manufacturer.
The main benefits of aftermarket keys are affordability and quicker availability. They can cost significantly less than OEM keys, sometimes forty to seventy percent cheaper, which makes them a budget friendly solution when you need a spare key or a fast replacement.
Many local or mobile locksmiths stock a selection of aftermarket blanks and fobs, which means you often don’t have to wait days for a replacement and you can get one on the same day. This convenience is why aftermarket keys are popular for older vehicles or second cars where cost and speed matter more than premium quality.
However, there are risks, quality can vary significantly between manufacturers. Some aftermarket keys may use weaker materials, have inconsistent electronics or poor blade quality. This can result in early wear, reduced remote range or signal issues, or even fail to programme or work reliably with the vehicle’s immobiliser or lock system.
In worst case scenarios, especially on newer cars with advanced security systems, a cheap aftermarket key can cause programming errors or gateway or immobiliser problems, leading to costly issues down the line.
What is a refurbished key?
A refurbished key is, essentially, a used or previously owned OEM key that has been reconditioned. The refurbishing process usually involves replacing worn parts like the housing, buttons or battery, inspecting or resetting the transponder and electronics and cleaning or repairing the internal circuit board so the key can be re programmed for a new vehicle if required.
Refurbished keys often offer a middle ground between OEM and aftermarket options. Since they originate as genuine OEM parts, they carry the same potential for compatibility and security, provided the refurbishing is done properly and the electronics, especially the chip and transponder, remain intact and functional.
When refurbished correctly, they can deliver many of the benefits of a brand new key, but at a lower cost than a new OEM version. That can make them an attractive option for older vehicles, second cars or for drivers simply wanting a spare without paying full new key prices.
That said, the reliability of refurbished keys depends heavily on the quality of the refurbishment process, chips must be reset properly, battery and components replaced and the shell must be sealed and durable. A poorly refurbished key can behave worse than a good aftermarket one, with inconsistent programming or premature failure.
Which type is right for you?
The best key depends largely on your vehicle type, budget and how critical reliability is for you. Here is a simple guide to help you decide.
Newer cars or vehicles with complex security systems, OEM keys or properly refurbished OEM keys are usually safest. Their guaranteed compatibility reduces the risk of programming or immobiliser issues.
Older cars, secondary vehicles or spare keys, aftermarket keys can offer good value, especially if sourced from a reputable locksmith and used as a backup rather than the main key.
If you want OEM level security at a lower cost, a refurbished key can be a solid compromise, assuming it is from a trusted supplier and carefully tested before use.
At Carsmith Midlands, we emphasise sourcing from reputable manufacturers, using certified blanks and programming keys with professional diagnostic tools to ensure reliability and compatibility, no matter which option you choose.
Why choosing a professional locksmith matters
Whether you choose OEM, aftermarket or refurbished, the critical factor is who does the replacement and programming. Even the best key blank will fail to work properly if it is programmed incorrectly or paired with the wrong frequency or transponder type.
Dealerships can be expensive and slow, especially for non standard models, older cars or in cases where original keys are no longer manufactured. A reputable mobile locksmith can often provide the same key type, perform programming on site and deliver results faster and more affordably.
With years of experience, we know how different manufacturers design their locking and immobiliser systems. That expertise matters, especially for premium brands or for vehicles with complicated electronic or remote locking features.
