Physical security
How to Protect Your Car From Keyless Relay Theft
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Keyless entry is convenient: walk up with the fob in your pocket, the car unlocks, push a button and go. That same convenience is what thieves use. Modern car theft is often quiet and electronic, with no broken glass. The good news is that the fixes are cheap.
This is one part of our vehicle security guide.
How a relay attack works
A keyless car constantly checks whether its fob is nearby. In a relay attack, one thief stands near your house with a device that picks up the fob’s signal, often through a front door or wall. A second thief stands by the car with another device that repeats that signal. The car thinks the key is right there, unlocks and starts.
It usually happens at night, with the fob sitting on a hook or table just inside the front door.
Keep the fob in a signal blocking pouch
A Faraday pouch or box blocks the fob’s signal completely. Drop the fob in when you get home, and keep spares in one too.
Test it once: put the fob inside, walk up to the car and try to open it. If it opens, the pouch isn’t doing its job.
Our pick
GoDark Vault key fob Faraday box· GoDark
A hinged metal box with a magnetic closure, easy to use every day. GoDark says it blocks the 315 MHz band used by most North American cars and the 433.92 MHz band used by many imports.
Downside: It holds one fob, up to about 3.2 x 1.6 x 0.9 inches, so measure yours and plan on one box per fob. GoDark doesn't publish lab test results, so run the test above. A pouch that passes the same test works too.
What good looks like: a pouch or box that passes that test, and is easy enough to use every day.
Keep the fob away from doors and windows
Even without a pouch, distance helps. Keep keys in the middle of the house, not on a hook by the front door.
Check your car’s settings and fob
Some cars let you turn off keyless entry, and some fobs go to sleep when they haven’t moved for a while. Check your owner’s manual or ask the dealer what your car and fob support.
Lock the OBD port
Some thieves skip the fob entirely. They get into the car, plug into the diagnostic (OBD) port under the dashboard and program a new key. An OBD port lock makes that much harder.
For extra security, unplug the port from its mounting spot, put the lock on it and zip tie it up under the dash where it’s hard to find. Then buy a dummy OBD plug and fit it in the original spot. A thief who plugs in there gets no connection and a lot of frustration. Keep the wiring clear of the pedals and steering column, and put the real port back before a mechanic or inspection needs it.
Our pick
Tune Saver OBD2 lock (BEM Auto)· Amazon
A key operated lock that covers the diagnostic port so nobody can plug in a programming tool. BEM Auto says it makes the lock in the USA from American-made aluminum and has sold it since 2017, which is longer than most OBD2 locks have existed. It installs without a professional and comes with a key.
Downside: The listing says it fits standard OBD2 ports but doesn't name vehicles, so check that it fits your car before you rely on it. It's a key lock, so keep the key where you can find it. A determined thief with tools can still get through it, so treat it as a delay.
What good looks like: a lock made for your make and model.
Back it up with a physical lock and a tracker
Electronic attacks are quiet, so a visible steering wheel lock is a good backstop, and a hidden tracker gives the police a location if the car goes anyway. The main vehicle security guide covers both, plus catalytic converters and break-ins.