Mercedes Spare Key Cost in the UK (2026 Guide)

Mercedes-Benz spare keys vary widely in price depending on the platform — FBS3 infrared keys on older models cost significantly less than FBS4 smart keys on the latest A-Class, C-Class and EQ vehicles.

FBS3 keys (W203 / W211 / older A and B Class)

FBS3 keys are an infrared platform used on Mercedes models from approximately 2001–2014. Replacement and spare keys for these typically cost £220–£280 fitted on-site.

FBS4 keys (latest A, C, E, S, GLA, GLC, EQ)

FBS4 is the latest Mercedes smart-key platform. Spare FBS4 keys typically cost £280–£400 fitted, depending on the model and year.

Why dealers charge more

Main dealers add labour, diagnostic and admin fees on top of the part itself. Independent locksmiths with FBS3 and FBS4 capability deliver the same work for substantially less.

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