How to Reset Key System Error In Nissan Altima (2019-2023)?

It’s morning, and you’re getting late for this important meeting.

You unlock your Nissan Altima, about to start it, and want to reach the spot as soon as possible.

But nothing happens when you turn on the ignition key (or press the brake pedal while pushing the ignition button – for keyless entry).

The car won’t start even after multiple attempts. Instead, you get a message on the instruments panel that says, “Key System Error: See Owner’s Manual.”

Sounds familiar?

Well, this is exactly what happened to my friend who owns a Nissan Altima 2019.

He eventually got it fixed, but not before wasting several hours and spending 200 bucks on the mechanic’s fee.

In this post, we’ll discuss different issues that trigger this message and their possible fixes so that you can spend your time and money on something productive.

What is the Key System Error In the Nissan Altima?

The key system error appears when the vehicle encounters a fault in its key, preventing the vehicle from starting or recognizing the key.

There’s a common misconception that this error only happens in vehicles with key-based entry systems.

I’ve seen an equal number of Altima vehicles with the keyless-entry system (aka. Intelligent Key Systems) that get this problem.

That’s why the warning message in those vehicles starts with “I-Key System Error” instead of “Key System Error.”

Many people think of these as two different issues, but they’re essentially the same.

Another misconception is that this problem only occurs in some particular Nissan Altima models.

Although it’s more widespread in Altima 2019 and 2020, I’ve seen it in other Altima vehicles that go as far back as 2012/2013 and as recently as 2023. Even some Nissan Infiniti, Rouge, and Sentra have reported this error.

Nissan Altima Key System Error, See Owners Manual Message: 8 Reasons

1. Weak Car Battery

A weak car battery is the most common reason for a malfunctioning keyless entry (or ignition) system.

The battery is responsible for sending a powerful electrical charge to the ignition system when you turn the ignition on or push the start button.

If the battery goes bad (normally happens if it’s 3-5 years old), it’ll send a weaker charge, which won’t be able to engage the starter motor.

As a result, the vehicle will not start. It might also result in poor communication between the key fob and the vehicle, triggering the ‘I-Key System Error’ warning message.

Most car owners don’t think about the battery when facing this issue, as the interior lights and instrument cluster lights of their vehicles are illuminated.

They don’t realize that a weak battery can run those lights without any issue, as they don’t require much power. But the same can’t be said about the starter motor, which requires a powerful jolt.

In some other instances, owners accidentally double-press the push button when exiting from the vehicle – unknowingly leaving it on ignition mode, which results in battery draining overnight.

Whatever the case, you should test the battery with a multimeter. A healthy battery should give you a reading of 12.6V or more.

I have also noticed that sometimes the battery is good, but the terminal connections are loose or corroded, leading to the voltage drop.

In such a situation, you’ll need to tighten or clean the connections before testing the battery again.

2. Damaged Proximity Keyless Entry Sensor(s)

The next thing we’ll check is the proximity keyless entry sensors.

These sensors are found in the doors/trunk area and help the Nissan vehicles’ keyless entry system communicate with the key fob to perform different hands-free functions when the fob is in close proximity.

If this sensor or its wiring connections get damaged, the keyless entry system will not work, and you’ll get the key system error message.

Therefore, check out the owner’s manual to find how many such sensors your car has, and then physically inspect them.

If any of them look to be broken or damaged, replace that sensor. It won’t be heavy on your wallet – costing only 20-25 bucks on eBay.

I have also noticed that many times the sensor itself is good. But the car owners overload stuff in their trunk area, accidentally disconnecting it and triggering the key system error message.

In such a situation, replugging the sensor to the connector should fix the issue.

3. Faulty Hood Latch Switch

If you have a Nissan 2013-2018 (2016 model, in particular), the key system error message can be the result of a bad/loose hood latch switch.

This switch is placed near the hood latch mechanism under the hood, and its primary function is to detect whether the hood is open or closed.

Many Nissan Altima owners have complained that this switch gets loose frequently and disconnects from the wiring harness.

This disconnectivity causes the vehicle’s security system to prevent the engine from starting – thinking that the hood is open even though it’s closed.

Sometimes, the switch itself is good, but the wiring harness is shorted or damaged, resulting in the former not working and you getting the warning message.

Therefore, if you’re getting the key system error message, but the fob is working, and the car is starting properly, the hood switch or its harness can be the culprit.

You can also use an OBD-II scanner here for confirmation. A faulty hood switch or harness will give you a B26FE error code.

4. Damaged Key Fob

The damaged key fob is another common reason for the key system error message.

Although these fobs have a decent lifespan of 4-5 years, any physical damage (being dropped frequently, for example) can prematurely affect their efficiency.

Why?

Because it can cause the fob’s transponder not to communicate with the vehicle’s security system, indirectly triggering the error message.

You can verify this by using the spare key fob. If the latter works fine, the problem is with the original fob.

Sometimes, the key fob itself is working, but the buttons malfunction, leading to the same error message.

Therefore, physically examine the key fob and its buttons. If they appear to be damaged, repair or replace them (depending on the severity).

5. Bad Key Fob Battery

Another thing you can check is the key fob battery.

The key fob is powered by a small battery. Located within the key fob housing, this battery gives the key fob the necessary power to communicate with the car’s key system.

When this battery cell gets older, the key fob’s signal-transmitting range will be reduced, and it will have problems communicating with the vehicle’s security system.

This intermittent connectivity can result in the key system error warning message.

Many car owners have complained that Nissan uses average-quality batteries in their key fobs that get fully drained in a relatively shorter period.

Therefore, if you have followed all of the methods so far, and the error message is still on display, replace the key fob battery to see if there’s any difference.

On the other hand, if you’ve recently changed the battery, check the battery contacts on the key fob.

These contacts can corrode over time, hindering the flow of electricity between the battery and the fob, leading to the latter working intermittently or not working at all.

6. Unchecked Remote Start Option

I haven’t personally faced this issue, but many Nissan owners have reported that their remote start-equipped vehicle gives the key system error warning when the remote start option in the vehicle settings is unchecked.

So, go to Settings > Vehicle Settings > Remote Start, and check this option.

7. Faulty Keyless Receiver Module

The keyless receiver module is another critical component in Nissan’s keyless entry system. Its purpose is to activate the key antenna for communication with the key fob.

If the key antenna is working fine, it’s worth checking the receiver module, too.

Why?

That’s because a faulty key receiver will not be able to process the key fob signals and authorize other vehicle systems.

The receiver module is a little complicated for DIY repair.

That’s why I recommend hiring a certified mechanic. They’ll test it and tell you whether you need to replace the wiring or the receiver module itself.

Conclusion

So these are some of the solutions you can try to fix the key system error warning message in your Nissan Altima.

If you’ve followed all of them, but the issue is still unsolved, I suggest going to a dealership.

At this point, we’ve checked for most of the common reasons for this problem, which leaves us with two components: IPDM (Intelligent Power Distribution Module) and BCM.

The dealership will test both of these components and will let you know if they’re good or need repair/replacement.

Frequently Asked Questions

What Does Nissan I-Key System Mean?

The I-Key (Intelligent Key) is Nissan’s proprietary technology that allows Nissan owners to remotely start their vehicles, lock/unlock the door, open/close the trunk, and roll down the windows with the help of a key fob.

How To Program The Nissan Altima Key Fob?

If you’ve got a new key fob for your Nissan Altima, you’ll need to program it to make it work with the vehicle. You can think of it as a pairing process for the key fobs.

You’ll need a key fob programming kit for this job, such as this one.

Here’s what you need to do:

1. Sit inside the vehicle and close all doors.
2. Plug the original key fob into the key fob slot located on the left side of the steering wheel.
3. Press the start/stop push button. Wait for 2-3 seconds, and don’t push the brake pedal.
4. Press the start/stop button once again to turn on the instrument cluster.
5. Plug the programming kit into the OBD-II port of your vehicle.
6. The kit I’m using will make two beep noises at this point.
7. Wait for 8-10 seconds and press the start-stop button. You’ll hear one more beep.
8. Wait for 8-10 seconds and press the start-stop button twice to start the ignition – don’t press the brake pedal. You’ll hear two more beeps.
9. Wait for 8-10 seconds and press the stat-stop button to turn off the ignition.
10. You’ll hear beeps again – three, this time.
11. Wait for 8-10 seconds and press the start-stop button to turn the ignition on.
12. A car icon on the instrument cluster panel will blink five times. It indicates that the vehicle programming mode is activated.
13. Remove the original key fob from its slot and put the new one in its place.
14. Press the start-stop button to turn the ignition on. The same car icon on the instrument cluster panel will blink five times, indicating that the new key fob is programmed and ready to be used.
15. Press the start-stop button to turn off the ignition.
16. Press the start-stop button to turn on the ignition without pressing the brake pedal.
17. Press the start-stop button to turn off the ignition again. Now we’ve exited from the key fob programming mode.
18. Remove the programming kit from the OBD-II port.

You can watch this video for further details.

What Is The Key System Fault Warning on a Nissan?

The Key System Fault warning on a Nissan indicates a problem with a Nissan vehicle’s keyless entry or ignition system as they cannot communicate with the key/key fob – preventing the vehicle from starting.

Why Does My Nissan Altima Not Recognize My Key Fob?

The most common reasons for the Nissan Altima not recognizing a key fob are the dead key fob battery or a damaged/aging key fob.