Key System Error on Nissan Altima: All Details Explained

As a Nissan Altima owner, you might have experienced the frustration of not being able to start your car. This is because a “Key System Error” message may flash on your dashboard. 

This error is not only inconvenient but can also be alarming, leaving you wondering what might be causing a key system error on Nissan Altima and how to fix it.

A key system error on a Nissan Altima can be caused by a faulty Intelligent Key, a faulty push button ignition, a faulty wiring harness, a low battery, or a malfunctioning engine control unit (ECU).

In this guide, we’ll be explaining everything you need to know about this error, including its common causes, symptoms, and potential solutions. So, stay with us by reading the entire content.

What Does Key System Fault Mean?

A key system fault in a Nissan vehicle typically refers to an error with the Intelligent Key system, which allows drivers to start their cars without inserting a physical key into the ignition. 

What Does Key System Fault Mean

This error can be caused by a variety of factors, including a low battery in the key fob, a malfunctioning key switch, or a more serious issue with the key system itself. 

It is a common issue that may be covered under warranty, and drivers should consult their vehicle’s manual or contact their dealer for repair and troubleshooting guidance. Other features, such as the tire pressure monitoring system, may also be affected by a key system fault.

Common Causes of Key System Error on Nissan Altima

Some Altima drivers may experience a key system error that prevents them from starting the car or using some key features. Here, we will discuss the common causes of the key system error on Nissan Altima.

Weak or Dead Battery

A weak or dead battery is one of the most common causes of key system errors on Nissan Altima. If the battery in your Intelligent Key is low, you may experience issues with starting the car or unlocking the doors. You can easily replace the key fob batteries, but if the issue persists, you may need to replace the car battery.

Malfunctioning Buttons

If the buttons on your Nissan Altima’s key fob are malfunctioning, it can cause a key system error. The buttons may be stuck, unresponsive, or damaged, preventing the car from receiving the proper signals to start or unlock the doors.

Faulty Switch

The switch that reads the Intelligent Key’s signal may also be faulty, causing a key system error. If the switch is damaged or not functioning correctly, it can prevent the car from recognizing the key’s signal, resulting in a key system error.

I-Key System Error

The I-Key system error is a specific error message that Altima drivers may encounter. This error occurs when the Intelligent Key system is malfunctioning or the key fob battery is low. You can refer to your Altima’s owner’s manual or warranty booklet for battery replacement instructions.

Tire Pressure or Hazard Lights

In some cases, the key system error may be triggered by other warning lights on the car dashboard, such as the tire pressure or hazard lights. If these warning lights are illuminated, it may be an indication of a more significant issue that needs repair.

Symptoms of Key System Error on Nissan Altima

Like any feature, the Intelligent Key system can encounter issues. Here are some symptoms of a key system error on the Nissan Altima:

  • Error Message: When you attempt to start the car, you may see an error message appear on the dashboard display that reads “I-key system error” or “Key system error.” This is the most common symptom of a key system error.
  • Failure to Start: If the Intelligent Key system is not functioning properly, the car may fail to start or respond to button commands.
  • Lights and Buttons: The lights on the car and buttons on the Intelligent Key may not function as expected.
  • Battery Limited Life: The battery life on the key fob batteries may be limited, which can cause issues with the Intelligent Key system.
  • Tire Pressure Warning: The Intelligent Key system may trigger the tire pressure warning light to appear on the dashboard display.

How to Fix Key System Error on Nissan Altima?

Some Altima owners may experience a common issue known as the “Key System Error” message, which can be frustrating and prevent the car from starting. Here are some troubleshooting steps to fix the Key System Error on a Nissan Altima.

Battery Replacement

One of the most common causes of the Key System Error is a low or dead battery. The Nissan Intelligent Key is powered by a small battery that may need to be replaced after several years of use. 

To replace the battery, check your owner’s manual or booklet for battery replacement instructions. Alternatively, you can visit a Nissan dealer or an automotive parts store to purchase a replacement battery.

Key Fob Replacement or Reprogramming

If the battery replacement does not solve the issue, the key fob itself may be damaged or malfunction. You can try reprogramming the key fob by following the instructions in your owner’s manual or by contacting a Nissan dealer. If reprogramming does not work, you may need to replace the key fob entirely.

Brake Pedal Switch Replacement

Another possible cause of the Key System Error is a faulty brake pedal switch. The switch is responsible for detecting whether the brake pedal is depressed, which is necessary to start the car. If the switch is malfunctioning, it may prevent the car from starting. A mechanic can replace the brake pedal switch to fix the issue.

Steering Lock Control Unit Replacement

In some cases, the Key System Error may be caused by a malfunctioning steering lock control unit. This component is responsible for locking and unlocking the steering column, and if it fails, it can prevent the car from starting. A mechanic can replace the steering lock control unit to fix the issue.

Can I Start My Nissan Altima Without A Key Fob?

Yes, it is possible to start a Nissan Altima without a key fob, but it depends on the model year and the type of ignition system installed in the car. Some older Altima models have a traditional key ignition that can be started with a physical key. 

Can I Start My Nissan Altima Without A Key Fob?

In contrast, newer models come with a push-button start system that requires a working key fob to be in close proximity to the car in order to start the engine. If the key fob is lost or the battery is dead, there may be alternate ways to start the car.

For example, using a key hidden inside the fob or inserting the fob itself into a special slot in the car’s dashboard. However, it’s recommended to refer to the owner’s manual or contact a Nissan dealership for specific instructions on how to start the car without a key fob.

How Do I Know If My Smart Key Battery Is Low?

The smart key is a convenient device that allows you to lock and unlock your car doors remotely. However, when the battery in your smart key is low, it may not function as it should. So, how do you know if your smart key battery is low?

Firstly, you may notice that the range of your smart key has decreased, and you need to be closer to your car to use it. Secondly, your car may not respond to the smart key at all, or it may take several attempts to lock or unlock the doors. 

Additionally, you may see a warning message on your car’s dashboard indicating that the smart key battery is low. If you experience any of these issues, it’s a good idea to replace the battery in your smart key to avoid being stranded without access to your car.


The key system error on Nissan Altima is a common issue that many owners have encountered. Through this discussion, all the details about the error have been explained. Remember that the error is often caused by a faulty key, a weak battery, or an electrical issue. 

In most cases, the error can be fixed by replacing the faulty part or reprogramming the key. If the error persists, it is recommended to take the car to a qualified Nissan technician for a professional diagnosis and repair.