The Honda Civic is a hugely popular compact car that made its debut in 1972.
Despite its impressive reliability record, it’s not uncommon for the alarm to go off randomly – for various reasons.
If you’re Honda Civic alarm keeps going off, this article is here to help…
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Why Does My Honda Civic Alarm Keep Going Off?
The most common causes of the alarm going off on a Honda Civic are a faulty hood switch, rodents chewed wiring, or a dying 12V battery. Other causes include door switch issues, a faulty body control module and a low key fob battery.
If your Honda Civic alarm is going off when it shouldn’t then by process of elimination, it shouldn’t be too hard to find the root cause...
1. Dying 12V Battery
A dying 12V battery or a battery with low voltage can cause a slew of problems, including activating the alarm of your Civic. This should really be the first thing you check as it’s a very common cause and it’s easy enough to check and fix.
Most 12V car batteries last about 3-4 years so it might be time for a new one.
It’s always worth cleaning the terminals first though and making sure the connections are tight and free from dirt, gunk and debris.
Tip: Clean the terminals using a toothbrush dipped in baking soda and water mixture
Failing that, the next step is to check the battery, you can do this with a multimeter or take your car to your local AutoZone who will test it for free.
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.
If you’re not confident doing this, take your car to any AutoZone who often offers free battery health checks.
2. Rodents Chewed Wires
A common cause of Honda Civic alarms going off is rodents chewing through electrical wires.
Although this may sound far-fetched it’s actually a very common problem – one that Honda is well aware of.
Honda sells a chili pepper-infused anti-rodent tape and even fits some components pre-wrapped in tape.
Rodents are known to nibble on electrical wires which are covered in soy-based insulation – this can lead to a wide range of problems, including triggering the alarm.
Here’s one owner’s advice on CivicForums.com:
“In other threads, we have seen rodents chew up harnesses near the bottom of the engine bay. May not be a bad idea to pull the panels and look around for any signs.”
3. Hood Switch Issues
Like most vehicles, the Civic equips a hood latch sensor which is essentially an electrical switch.
It is designed to trigger an alarm if someone tries to force open the hood, however if it is broken or clogged with dirt this can trigger the alarm.
Dirty Hood Switch
Due to the prominent location of the hood switch, it is very prone to getting dusty, dirty and grimy – the accumulation of which is enough to cause alarm issues. Corrosion and rusting of the hood switch is also very common, which can also trigger the alarm.
Give the hood latch a thorough clean and make sure it is completely free of dirt and debris.
Faulty Hood Switch
It’s not uncommon for the hood switch to develop a fault or get damaged from the bumps of driving, from slamming the hood or from exposure to weather.
If the switch that monitors whether the hood is open or shut isn’t working then this will impact the alarm.
If you’re mechanically inclined it’s not too difficult to replace these, if not have your Honda dealer take a look.
You can test whether the hood switch is working by using a continuity tester, measure across the connector (switch) and simulate opening and closing the hood latch with a screwdriver.
- When the hood is open you should have continuity
- When the hood latch is closed you should have an open circuit
Here’s what Honda Civic owners had to say:
“Bought a new latch from the dealership since no parts people have the part. Haven’t had a problem since. Upon review the old switch, it was crunchy and probably had water get in to it. This is a fairly known Honda/Acura problem.”
“We actually needed the hood latch assembly replaced. It would have been $180, but we have HondaCare warranty and we paid a $100 deductible. It is back to normal.”
4. Faulty Door Sensor
A faulty door latch sensor is a common cause of Honda Civic alarms going off.
Similar to the hood latch sensor, your Civic alarm monitors the doors to make sure no one is opening them.
It’s a good idea to give all door latches a clean and some lubrication with WD-40, open and close the doors to work it in.
Water leaks into the door lock actuator can corrode the wiring and electrical connections.
5. Trunk Switch
Similar to the door sensors and hood switch, the trunk switch can also be a common culprit when it comes to alarms going off at random.
Switches are a common point of failure in the alarm circuit of any vehicle.
The trunk switch may become damaged and would therefore cause the alarm to go off at random.
6. Faulty Body Control Module
A common reason why a Honda Civic alarm keeps going off is due to a faulty body control module.
The body control module or ‘body computer’ is the electronic control unit responsible for monitoring and controlling various systems associated with the vehicle’s body such as the alarm, immobilizers, power windows etc.
The body control module can develop faults, damage, corrosion on the pins or connections can become loose.
You can typically pick one up for under $1000 and if you’re not mechanically inclined it’s probably best to have someone at Honda fit it for you.
Other common symptoms of a bad BCM include:
- Repeated battery drain
- Starting problems
- Erratic electrical functions e.g. horn, wipers, lights, lights on the dash
- Security and alarm system problems
7. RFI and EMR
RFI is Radio Frequency Interference and EMR is electromagnetic radiation, both of which can cause the alarm to be triggered on your Civic.
For example, parking underneath overhead power lines will expose your car to high amounts of 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.
Here’s some advice from some owners:
“There probably is some sort of RFI being generated around where you park at work which is making your car go insane.”
“If it happens at home, but nowhere else, check your immediate neighborhood to see if one of your neighbors is a HAM radio operator… (look for big antennas, or personalized license plates with their call letters on their cars. In a nutshell Ham operators often transmit very strong signals and that can (and often does) overload poorly shielded alarms and set them off. I’ve set off many alarms in mall parking lots with my 45 watts (2m) transmitter in my car, some home setups transmit several hundred watts.”
8. Low Key Fob Battery / Faulty Key Fob
As the key fob also has controls linked with your Civic alarm system, a faulty, damaged or malfunctioning key fob can send an incorrect signal, which may trigger the alarm. A low key fob battery can cause the alarm on your car to go off at random.
Try using your spare coded key – if the problem goes away then you know you’ll need to replace the battery in your primary key fob.
It’s also advised that you don’t carry big metal objects, electronics or a second coded key on the same keyring as your primary key fob as this can lead to problems also.
It might also be worth giving the inside of your key fob a clean as these can get filled with dirt which could be causing the alarm issue.
In summary, if you suspect your problems might be key fob related you can try the following:
- Check and replace key fob batteries
- Clean the key fob
- Reset the key fob
- Reprogram the key fob
Here’s what a couple of drivers had to say:
“Change the battery in the key fobs!! It stopped mine from going off.”
“I’d say the first thing to try would be to spend the $6 and get a couple of new batteries for the FOB and if it still does it then you have a bigger problem. I always try to weed out the simple problems 1st. If $6 fixes the problem then you won’t have to spend any money taking the car to the dealer to diagnose the problem.”
Unlock or Lock With Keys
Some owners recommend unlocking and locking the car with the keys in the door, instead of the fob if the alarm keeps going off.
There is a plug electrical connector under the hood, by the hood latch that when disconnected can disable the alarm.
Disconnect the Battery
Sometimes mysterious alarm problems can disappear with a simple reboot, there are no guarantees here but it’s worth a shot.
Disconnect the battery for 20 seconds and this resets many of the electronics in the vehicle.
Check For Warning Messages
When the alarm occurs can you see any lights or warning messages on the gauge cluster?
This can give a clue as to what’s causing the alarm e.g. ‘Hood Ajar’.
Take it to a Honda Dealership
If needed, take your Honda 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 (run computer tests to see exactly what is triggering the alarm) for no money as they plan to make money for the repair of your vehicle.
If you’re Honda 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 Honda’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.
Diagnosing Faults With a Scanner
Another possible option if you’re having alarm issues is to use an OBD2 diagnostic scanner tool, this can help narrow down what is causing the alarm.
These are fairly easy to use, you simply plug them into your car – there’s usually an OBD2 port under the steering wheel.
Once you have the scan codes you can research these online specifically for the Civic.
There are also OBD apps available so you can connect your car straight to your smartphone (either with a cable or Bluetooth) without even needing a scanner.