The Hyundai Elantra is one of North America’s most stylish compact sedans.
As with any vehicle, the Elantra’s alarm can be triggered for mysterious reasons.
In this article, we’ll investigate the causes and solutions for the Elantra alarm going off at random…
Table of Contents
Why Does My Hyundai Elantra Alarm Keep Going Off?
A faulty hood switch, low key fob battery, a dying 12V battery, and accidental press of the panic alarm can trigger the Hyundai Elantra’s alarm, and are some of the main causes of random alarms.
1. Faulty Hood Switch
The most common cause of false alarms on a Hyundai Elantra is a faulty hood switch. If your Elantra’s hood switch is dirty, damaged or broken, it can trigger the alarm.
- The hood switch is part of the Elantra’s factory alarm system.
- It is designed to detect break-ins or forced entry of the hood
- When you lock your Elantra, the alarm is armed.
Its a good idea to check that the hood switch is free of debris and dirt.
If you’re mechanically inclined you can test the switch using a continuity tester.
If the switch is faulty you can replace it yourself or have a reputable mechanic take a look for you.
To highlight how common this issue is, here’s one owners post from Hyundai-Forums.com:
“Sounds like the infamous hood switch issue. Check and make sure the rubber stopper that depresses the hood switch hasn’t gone missing and it’s entirely possible that the switch itself has gone bust.”
Another owner on Reddit shared the following useful advice:
“Look in the engine bay I think on the passenger side, there is a button, it is supposed to have a corresponding rubber bumper on the hood that presses the button. The rubber bumper is either missing or has collapsed slightly.
Set the alarm and press on the passenger side of the hood near the fender headlight area. If the alarm goes off you have your problem. The updated rubber stopper is like $4 from the dealer.”
2. Faulty Switches
Aside from the hood switch, there are door switches and a trunk switch that could be faulty. These simple mechanical devices, when damaged, dirty or broken can cause random alarms as they are an integral part of the alarm system.
The switches simply detect if the door, trunk or hood is closed when the alarm is armed. They can give false readings when faulty.
If you suspect you have a faulty switch you can take your car to your nearest dealer and have them run some diagnostic tests in order to pinpoint the faulty switch.
On the Hyundai Sub Reddit, here is what one owner had to say:
“Every time I’ve had an issue like this with an alarm, it’s been because of the door and/or hood open/close sensor going bad or not making good contact anymore. I would try there and check all of them to make sure they’re depressing the sensor closed all the way.”
3. Low Key Fob Battery
A low key fob battery is a common cause of mysterious alarms on the Elantra. For the sake of a few dollars its worth replacing the fob battery to rule out this possible cause.
- The Elantra’s key fob uses a CR2032 battery, make sure you insert it the right way up, and its best to buy a good quality battery.
- Make sure the inside of the fob is clean too, you can remove any dirt and debris with a cotton swab and some rubbing alcohol.
Here is what one Elantra owner on Reddit had to say:
“As someone who had the exact same issue with a 2010 model, replace your key fob battery. I did and have yet to have the alarm issue again. Apparently the way of signaling that it’s low on batteries is to hit the panic button randomly.”
Similarly, a faulty key fob can cause alarm issues – although this is less common.
You can try using your spare fob (keep the other fob at a safe distance), or speak with your local Hyundai dealership.
4. A Weak or Dying 12V Battery
An Elantra’s alarm can be triggered at random due to a weak or dying 12V battery. When the battery’s voltage is insufficient, it can cause the alarm to go off unexpectedly.
Typically 12V car batteries have a lifespan of about 3 to 5 years. Therefore, it may be due for a replacement.
Before swapping your car’s 12V battery, it is worth taking the time to disconnect the battery, clean the battery’s terminals, reconnect the battery, and ensure that the connections are tight and there are no obstructions.
You can clean the terminals using a toothbrush dipped in baking soda and water mixture.
If you have a multimeter in your garage, you can do a battery check yourself – we’ve included a short guide at the end of this article – essentially the battery should measure between 12.2 and 12.6 volts.
If you’re unsure, take your car to your nearest AutoZone – most offer free battery health checks.
5. Accidental Press of the Panic Alarm
One simple and often overlooked reason for a false alarm on the Elantra is accidentally pressing the panic alarm on the key fob.
This can be easily done when the fob is in your pocket, especially when wearing tight clothes or bending down to pick something up.
Here is what the Elantra’s owner’s manual says:
“Press and hold the Panic button for more than one second. The horn sounds and hazard warning lights flash for about 30 seconds. To cancel the panic mode, press any button on the remote key.”
6. Aftermarket Alarm System
If your Elantra has an aftermarket alarm fitted (one that did not come fitted as standard with the car) then this may have been incorrectly installed or it may be faulty.
It may also have additional sensors which might be damaged or overly sensitive.
Aftermarket alarm systems are often more sophisticated than a typical factory-installed car alarm but are often installed by people who aren’t mechanics.
If you have an aftermarket alarm that’s causing you problems it’s best to have it examined by your nearest Hyundai dealership or an auto-electrician.
7. Damaged Wiring
Damaged electrical wiring can cause a wide variety of issue, especially with the alarm system.
Damaged, corroded or faulty wires aren’t easy to find and you’ll need to have an auto electrician carry out some fault finding on your car.
A common point of failure for electrical wiring is in and around the doors,.
If you’ve had some kind of water leak in your car then this issue is one to investigate.
8. Electrical Interference
Parking underneath or within close proximity of overhead power lines can cause false alarms from your Elantra.
If you notice your alarm goes off, but only in certain locations, then it could be some kind of electrical interference from power lines or even a HAM radio.
This phenomenon is caused by electromagnetic radiation (EMR) which can interfere with the electronics on your alarm system.
If you suspect this is the cause, try parking somewhere else out the way.
Related: 4 Most Common Problems With Hyundai Elantra (Explained)
Alternative Suggestions
Check Bluelink
If you have the Bluelink app you can check this for clues as to why your alarm is going off.
It is best to check the app when the alarm is going off.
Disconnect the Battery
Sometimes mysterious alarm problems can disappear with a simple reboot, there are no guarantees here but it’s worth a try.
Disconnect the battery for 20 seconds and this resets many of the electronics in the vehicle.
Make Sure All Doors Are Shut Properly
This is sometimes overlooked, but make sure all doors, trunk and hood are shut properly.
Check For Warning Messages
When the alarm occurs can you see any lights or warning messages on the instrument panel?
This can give a clue as to what’s causing the alarm e.g. ‘Hood Open’.
Take it to a Hyundai Dealership
If needed, take your Elantra to the dealership.
Tell them you are NOT paying for a check on what the problem might be.
Ask them if they will check it for free.
Most dealerships and other places do quick/initial diagnosis for no money as they plan to make money for the repair of your vehicle.
If you’re car is still under warranty then they should fix and resolve the issue for free.
Check for Recalls or TSBs:
By entering your car’s VIN number on Hyundai’s recall page or the NTHSA’s Safety Issues & Recalls page you can determine whether or not there is a TSB or recall for your vehicle and if there is you’ll want to get it addressed.
A recall is issued by a vehicle manufacturer for issues that are safety-related, while a TSB covers components that may be malfunctioning but don’t compromise the safety of the vehicle.
How to Test the 12V Battery
How to Test the Battery
- Before testing, remove the surface charge from the battery, this allows for an accurate reading.
- Simply turn on the headlights for 2 minutes then turn off.
- Set the multimeter dial to the ’20 Volts’ setting.
- Make sure the car is turned OFF
The multimeter will have a red probe and a black probe:
- The red probe is for making contact with the positive terminal
- The black probe is for making contact with the negative terminal.
Measure across the battery terminals.
- The meter should display a reading, if the battery is fully charged the voltage should be between 12.2 and 12.6 volts.
- Anything under 12V and the battery should be charged or replaced.
Resources
https://autoservice.hyundaiusa.com/campaignhome
Hyundai Elantra 2018 Owners Manual
