Push-To-Start Key Not Detected — What’s Actually Wrong?
A push-to-start key that stops being detected is usually a dead or dying fob battery, not a car fault — the fob still needs power to transmit its signal even though there is no ignition key to turn. Replace the small coin battery inside first; if that does not fix it, the fob or its programming may need attention.
The dashboard says “key not detected” while the key is sitting right there in your pocket or the cupholder, and the instinct is to assume something in the car has failed. Usually it has not.
Start with the battery
Push-to-start fobs run on a small coin cell battery, the same type used in a watch. That battery has one job — keep the fob transmitting a signal the car can detect — and when it runs low, the signal gets weaker before it stops entirely. A weak-but-not-dead battery often causes intermittent detection, which explains why it sometimes works and sometimes does not.
| Symptom | Likely cause |
|---|---|
| Works sometimes, not others | Weak battery — replace it |
| Never detected, replaced battery, still nothing | Fob programming or antenna issue |
| Works only very close to the car | Weakening battery |
| Stopped suddenly after water exposure | Fob damage — needs inspection |
Replacing the battery yourself
Most fobs have a small release catch or screw that opens the case. The battery is usually a widely available CR2032 or similar, sold at most pharmacies and hardware stores. This is a five-minute job on most fobs and worth trying before assuming anything more serious is wrong.
If a new battery does not fix it
- The fob may have lost sync with the car’s system and need reprogramming.
- The fob’s internal antenna or chip may have failed, which a battery cannot fix.
- The car’s own receiver may have a fault, though this is far less common than a fob issue.
Full detail on programming and reprogramming is in key fob programming.
What if you have a spare fob?
Try it. If the spare works normally, the problem is specific to the first fob — battery or internal fault — not the car. If neither fob is detected, the issue is more likely on the vehicle side, or both fobs have lost sync at once, which does happen after certain battery disconnections or software updates.
Booking it
Tell us what you have already tried — new battery, spare fob — and we can usually narrow it down before arriving. Ranges are on the prices page.