Circumventing Key Sentry


So you have a new(ish) car with key security features, transponder, resistance security, RF interrogating, near field whatever,… and you’ve lost one of your fobs. Most of your hope is lost but not all.

Our car is a Dodge Caliber, 2007. Doesn’t have a security system, just near field transponder based keys that provide a theft deterrent. We’ve lost 1 of the two FOBs received when we bought the car


There are several options if you lose a fob. I’ll list them below:
1) Live with only one FOB. With two people driving the car, this is hard to deal with and even worse if your ONLY car key is lost
2) Pay the dealer $300 or so to get a new fob with door locks etc and transponder
3) Pay the dealer $150 for a basic transponder key, no keyless entry
4) Pay $30 for a cut key from the dealer that will do nothing but open the locks on the car (the car will not accept a basic cut key, the engine will not start)
5) Purchase a FOB with keyless entry, uncut from ebay (about $70 to $100) and get a locksmith to cut it and program it (probably $40 to $60 for his/her services). Total potentially $150 or so, atleast unlinke option 3 you get keyless entry included

6) and this is the option I’ve chosen, get 3 basic keys cut from dealer, $40 (two mains and a spare), then figure out what type of transponder your key is, near field, contact based, etc. Mine is near field or RF, turns out it has to be – from some quick testing, within 5 cm’s or less. So I’ve taped the original FOB to the bottom of the steering column, close enough that the car is able to interrogate it and recognize its signature, and use the cut keys going forward for regular use. The FOB just stays in the car under the column. Only problem is no keyless entry. So,… search around and get a basic keyless entry FOB kit from canadian tire or whatever you want. You can even get remote car starting if you wish while you’re at it. For now, I haven’t purchased a keyless entry FOB kit yet, but thats the direction we’ll move in so we each have keys and FOBs for convienience.

Now… you can prevent this issue from happening by purchasing a new FOB off ebay for $100 or so. Why? Because you can get it cut locally, and then program it yourself – to program yourself you need TWO original FOBs – Car makers assume that if you have two fobs, you must be the owner so they allow you to program it yourself. You aren’t actually programming the key though, you’re training the car to recognize the key, and accept its response when interrogated by the car computer. But then if you have 2, why would you think of purchasing a 3rd 😛 You probably wouldn’t…

So anyways you ‘cut’ it, 6 is the least expensive overall. But hey, if you have $300 to spend, definitely getting a new FOB is the most straight forward way.

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