Why Does My Nissan Altima Say "No Key Detected"? We Explain

There's nothing more frustrating than not being able to access your car when you need to. If you have a Nissan Altima with keyless entry, you might have run into a problem where the car says "No Key Detected". If this problem is keeping you from getting into your car, or starting your engine, you might wonder what is causing it.

The most common cause of your key fob not being detected in your Nissan Altima is that the key fob battery is dead. If the key fob is still good, there could be a problem with another system. The car's battery may be low or dead, and it is also possible that there is a problem with the car's remote key functions.

In this article, we'll explore the reasons why your key is not being detected by your Nissan Altima. We will also look at how you can address these problems.

Why Can't My Nissan Altima Detect the Key?

When your Nissan Altima says, "no key detected", it means that the car is having trouble detecting the key fob. The keyless entry system in your car consists of a receiver in the vehicle and a short-range radio transmitter in the key fob. The receiver in the car constantly listens for the radio signal from the key fob. When the receiver successfully detects the key fob, it allows you to perform key functions, such as opening the doors and using the push-start button.

Sometimes, the vehicle fails to detect the signal from the key fob, which results in a no key error message. This can be very frustrating, as it prevents you from operating your car at your convenience.

There are many reasons why this can happen. Here are some of the reasons why your car might not detect the key fob.

1) Dead Battery in the Key Fob

The most common cause of a "no key detected" problem is a dead battery in the key fob. When the battery is dead, the key fob won't be able to send signals to the receiver in the car.

2) Faulty or Damaged Key Fob

A damaged or faulty key fob is another very common reason why the key might not be detected. Physical impact or water damage could keep the key from working and being detected by the car.

3) Weak or Dead Car Battery

Another common reason that your Nissan Altima's key might not be detected is that the car's battery is too weak to power the car's keyless entry system. The antenna and receiver in the keyless entry system require a certain voltage to operate. A weak car battery will not be able to provide sufficient voltage for these systems to work, which will result in the keyless entry system failing.

4) Key Needs to Be Reset

The key fob needs to be specially coded to the car that it works with. This is done by the manufacturer, but some circumstances can cause the key to no longer work with the car that it has been paired to.

Usually, the key will need to be reset if the battery has been dead for a while. Some drivers also complain that their key no longer works for their car if it has been too close to another key fob.

5) Electronic Problem in the Keyless Entry

This is one of the less common causes of your Nissan Altima's key not being detected. Sometimes there could be a hardware or electrical problem with the car's keyless entry system. This could have to do with the body control module or the antenna that the keyless entry system uses to communicate with the key.

How Can I Enter My Car?

Many drivers are not aware of this, but your key fob contains an emergency key. To access your emergency key, and access your Nissan, follow the steps below:

• Flip over the key fob and look for the latch release button.
• Unlock the latch release button and pull out the hidden emergency key from the key fob.
• Use the emergency key to open your car from the driver's side door.

While this emergency key is very useful for getting into your Nissan Altima, it will not help you start the car. If you want to start your car when the key isn't detected, you will have to follow another simple procedure.

How Can I Start My Car?

Once you successfully access your Nissan Altima, you might wonder how you're going to start the car if the key fob is not detected. Fortunately, there's also an alternate way to start the car if the key fob is not functional.

There are two ways to start your Nissan without a functioning key.

The simplest way to start your car when the key fob is not detected is to press the key fob against the start button while holding down the brake. Press the start button and the car should start.

If the previous method did not start your car, you can also start your Altima using the key fob port. This is located on the dashboard to the left of the steering column.

Insert the key fob into the port and start the car. Tap the brake pedal and press the start button. The engine should come to life.

How Can I Fix This?

While it's still possible to enter and start your car when the key fob is not detected, this is inconvenient. If you're trying to get the keyless entry capability back on your car, you'll need to find the cause of the problem and fix it.

Here are some ways to fix the most common problems that cause your Nissan Altima's key to not be detected.

1) Replace the Battery in the Key Fob

If the battery in your key fob is dead, it will need to be changed. You can have the key fob battery replaced at a Nissan dealership, but it's much cheaper and easier to change it yourself. Here are the steps you need to follow to replace the battery in your key fob.

• Remove the emergency key from your key fob.
• Insert the key into the slot at the bottom of the key fob and turn it slowly. This will open the key fob housing.
• Take note of the direction the battery faces and remove it from the key fob.
• Insert the replacement battery, making sure it faces the same direction as the one you just removed. The negative side of the battery should be facing out, while the positive side of the battery should be facing into the key fob. Make sure the battery makes good contact with the metal contacts inside the key fob.
• Close the key fob and test it to make sure that it is working.

2) Replace the Key Fob

If the key fob has been damaged or is faulty, then you will most likely need to replace it. You can get a replacement key from a Nissan dealership.

You can also buy a replacement key fob, and have it reprogrammed to your car by an experienced locksmith.

3) Charge or Replace the Car Battery

A weak or depleted car battery poses more serious problems than not just detecting the key fob. Other systems in the car might malfunction when the battery is weak. If the cause of your keyless entry problem is a depleted battery, you will need to charge it. You can do this by allowing your car to idle for 25 to 30 minutes. A faulty battery will need to be replaced.

4) Reset the Key

The simplest way to reset your key fob is to insert it into the key fob port and start the engine. If your car does not have a key fob port, you can reset your key fob by tapping it against the start button instead.             

5) Repair the Keyless Entry System

The keyless entry system in your Nissan Altima consists of several different electronic parts. As a result, it is difficult to diagnose the problem without proper knowledge and experience.

You will need to have an automotive electrician inspect the car to find and fix the cause of the problem.

Conclusion

It's very frustrating when your Nissan Altima's key fob isn't detected when you need it. This can waste your time and keep you from getting where you need to go. Luckily, if you know how to deal with it, you can not only open your car door, but you can also get the engine started and drive it like normal. You can access your car using the emergency key hidden inside the key fob. You can start your car by either tapping the key fob against the start button or placing it in the key fob port on your dashboard.

The most common reason your key fob won't be detected is that the key fob battery is dead. Replacing the battery usually solves this problem. Other reasons this could happen are because the car battery is weak, or there's a problem with the car's keyless entry system. You might also have a faulty key fob.