3 Reasons Why Prius Key Detected In Vehicle

If a warning appears on the dashboard or the computer screen stating that the Key detected in the vehicle while you are driving, there could be several issues causing this problem. Someone did not close the door correctly, the trunk is open, the battery in the key fob is low, or the sensors cannot detect the key fob.

The Warning Light Key Detected In Vehicle Continues to Flash Off And On

So you’re just driving along, hitting down to the nearest golf course, and suddenly your Prius starts beeping and whining. You look at your dashboard behind the steering wheel and see that the words Key Detected In Vehicle flash on and off in big white letters. Many people do not understand the purpose of this light, as the key is supposed to be in the vehicle. 

There are a few reasons this warning light goes off.

One of the passenger’s or driver’s doors is not closed all the way

We all forgot to close the door the right way from time to time. Sometimes, we will exit our vehicles, close the door, and then walk away. But then a little voice in our head says to press the lock button on our vehicle’s key fob to make sure we locked our car. 

When we press the lock button on the key fob, our Prius does not make the beeping noise we recognize to mean that the vehicle’s doors are locked. Now we must turn around and investigate all the doors to see which one is not closed. 

As we drive in our vehicles, this warning sign will appear when one door is not fully closed all the way. So asking everyone in the vehicle to open their doors and close them will fix this issue.

The Trunk Is Not Closed 

Sometimes we do not press the lid down all the way when we close the trunk. The hood of the trunk stays closed, but the sensors around the trunk alert the computer system that the trunk is not closed all the way. The trunk will not lock correctly from time to time.

But if you notice the trunk of your vehicle no longer locks whenever you open and then close it, it could be an issue with the latch. 

Depending on how hard you close the hood of the trunk, the latch can wear out quickly or slowly. If you’re the type of person who slams the trunk door closed, be prepared for a big repair bill if you stop this habit. And the repair bill will be even bigger if you have a motorized trunk lid that opens and closes at the push of a button.

Something Blocks The Key Fob From Its Sensor

Many people on Prius Forums have complained about the Prius key detection issue. One common complaint is that the warning will appear while the vehicle is in motion. 

Some Prius models allow their drivers to activate the vehicle without placing the key into the ignition slot. But some drivers feel more comfortable putting the key into the ignition as they always have. So when the vehicle is in motion, why does the warning light appear if the key is in the ignition? 

It could be because the sensors in the vehicle are trying to detect the key fob. If the Prius’ key is in the ignition, then the key fob should be nearby. When the key is in the ignition, but the vehicle cannot detect the key fob, it will scan continuously for the key fob. 

For example, one forum post said that the Prius Key detection warning light will stop when their wife pulls the key fob out of her purse. The material in the purse must have been thick, so the sensor in the vehicle could not detect the key fob. 

Do you insert the key into the ignition but keep the key fob in your briefcase, pocket, or purse? Next time you drive your Prius, pull the key fob out and see if the warning light goes away.

Poor Battery Life In The Key Fob

When the Prius unlocks its doors, it will scan for the key fob to know that the driver is nearby. If it cannot find the key fob, the warning light will appear on the dashboard and it will not go away until it detects the key fob. 

We’ve already established that a thick material could prevent the sensors in the Prius from detecting the key fob. But, maybe the battery in the key fob is low. 

When the battery is low, it cannot communicate with the sensors in the Prius. You will know when the battery in the key fob is low when you have to press the lock and unlock buttons multiple times for them to work. 

You will also have to move closer and closer to the vehicle so the signal from the key fob can reach the Prius’ sensors.

How To Replace the Battery in The Key FOB

Replacing the batteries in the key fob is easy. Most key fob batteries are small. Usually smaller than a coin like a penny. You can buy key fob batteries at any Walmart, Target, or auto shop. Some gas stations carry key fob batteries. 

Some Fobs use AAA batteries. Open the underside of the key fob to know which batteries to use. Other key fobs require the driver to unscrew the key fob battery latch with a screwdriver. Once the latch is open, replace the batteries and close the latch again. When you are driving your Prius, see if the warning light appears again.

Conclusion

A key fob with the low battery can activate the Prius Key Detected in Vehicle light. Also, the light may appear if it cannot find the key fob in the vehicle while the driver and the vehicle are in motion. Replacing the key fob batteries shouldn’t cost more than $10 and you can do it yourself. Also, check the doors around the vehicle to see if one of them is open.