Proximity Card Suddenly Does Not Work

I walked into a gym with my proximity card. I left my iPod on the treadmill as I walked out to get a drink of water. I swipe my card to enter the gym again. The card does not work.

What happened?

Is there some way I can restore my card?

I don’t want to pay another 50 dollars for a new card!!

Can I hack the proximity card reader?

I’m not especially concerned about the iPod, as it’s a 2nd gen. nano that’s been through the wash once. It’s just the cost of replacing the card.

What is a proximity card? What is it normally used for?

“Proximity” means that the card can be read just by being NEAR the device, and doesn’t need to actually touch it.

I’m the computer guy at work who deals with these things. Sometimes they do wear out, but that can take years. But if they’re folded or cracked, game over. Usually the problem is not in the card at all, but in the software that reads it. Don’t be afraid to try it again the next day and/or ask the management about it.

Usually what happens is that it will get bent or flexed once too often and the antenna cracks in it.


The loop around the perimeter is the antenna. There are several variations on the theme, but that’s the basic design.

I demagnetize cards. Especially hotel keycards. I’ve done it to my “teacher-unlocking-door-by-waving-card-over-a-wall-mounted-pad” card. Is that what you mean?

I’d have to pay if I lost it, but I just take it down to the office and they “reinitialize it” (remagnetize it).

FYI, I’ve always heard those referred to as “RFID cards”. (Radio frequency ID cards, they basically have a little radio antenna that responds to a specific frequency from the door scanner.)

Do proximity/RFID cards lose sensitivity with age?

I noticed that I had to press my card against the reader toward the end of its lifespan, and that I often had to unwrap the lanyard from around it to make it work. The last time my card worked, I had to unwrap the lanyard and rub the card against the reader.

I did often throw around the proximity card … I wonder if that contributed to its demise.

Not as a rule. No moving parts and no battery to degrade. That being said, any/all electronic device will eventually degrade. Generally they’re designed to outlast their projected usefulness. But some will fail prematurely, thus the MTBF (Mean Time Between Failures) rating.

Or at least designed to function through their warranty period by a couple of days…

Throwing it around? Maybe. If you managed to separate the layers allowing some component to corrode from exposure to the atmosphere.

Magnetics are only really involved with cards you ‘swipe’ (i.e. credit cards). Well, it’s all electromagnetism, but proximity cards use radio waves to induce a small current in an RFID chip (or words to that effect). IOW you can’t damage proximity cards with magnetic fields like you can bank cards. Bending them too much & too often is the most likely cause, it breaks the tiny wire in the above picture.

If you keep the card in a wallet you can do this over time, but I’d still demand a free replacement, I would consider that normal wear & tear not abuse.

I worked in IT for years and one day I got the brilliant idea to take my card to the HR girl who makes the company ID badges and said, “Can you punch a hole in this with the badge machine?” I wanted to clip it under my ID badge which was on a badge reel so it’d be easy to bring close to the reader (I was constantly going in & out of the mainframe/server computer room all day). Bad idea. It of course broke that little wire that runs along the edge and immediately stopped working. They didn’t make me pay for a new one, my boss just said, “Ah, next time ask first…”