Check these first
- The fob battery. The most common cause by far. Range shrinking over a few weeks, or the car only answering when you stand next to it, is the classic sign. Most fobs take a flat coin cell printed on the old battery; it is a few minutes' job with a small screwdriver.
- Interference. Strong radio sources nearby can drown a fob out: some parking garages, cell towers, even another phone or fob in the same pocket. Try again a few steps away.
- The car's own battery. A weak car battery can make the car ignore a perfectly good fob. If the dash is dim or the car cranks slowly, start there.
- A second fob. If the spare works, the problem is the first fob, not the car.
Getting in and going with a dead fob
Almost every modern fob hides a mechanical key that slides out of the case, and the driver's door has a key cylinder, sometimes under a small cap on the handle. On a push-to-start car, the owner's manual shows where the car can read a weak fob directly: usually by holding the fob against the start button, or placing it in a marked spot in the console. That gets you home to change the battery.
When it is more than a battery
- Water. A fob that went through the wash or into the pool may work for a day and then fail. Open it and let it dry fully before trying a new battery.
- Out of sync. Some fobs lose their pairing after a battery change and need to be paired to the car again.
- Worn or broken. Cracked cases, worn buttons and broken circuit boards are common on fobs that live on a heavy key ring.
A fob that needs pairing or replacing is a job for key fob replacement or car key programming. If you have lost the fob altogether, our guide to losing a push-to-start fob explains what happens next, and chip keys and fobs explained covers how fobs talk to cars.
Questions people ask
How do I know if my key fob battery is dying?
The range gets shorter over days or weeks, buttons need pressing more than once, or the dashboard warns of a low key battery. A fresh coin cell usually fixes it.
My car says key not detected. How do I start it?
Most push-to-start cars can read a weak fob held against the start button or placed in a marked spot in the console. Your owner’s manual shows where.
Does a fob need reprogramming after a battery change?
Usually not, but some do. If the fob still does nothing with a new battery, it may need pairing to the car again.
Can you program a new fob without the dealer?
For many makes and models, yes. Text the make, model and year and we will tell you before we drive over.