Honda S2000 Alarm Going Off? (13 Causes & Solutions)

The Honda S2000 is a sports car that offers great performance for its value. 

However, even sports cars are not immune to the occasional alarm system going off. 

If your S2000 alarm keeps going off, read this article to find out some possible fixes…

Why Does My Honda S2000 Alarm Keep Going Off?

A Honda S2000 alarm is usually triggered by a faulty hood switch or door switch. Other common causes include 12V battery issues, key fob issues, and a defective keyless entry module. 

1. Faulty Hood Switch

A faulty hood switch is a common cause of unwanted alarms for Honda vehicles (S2000 included).

The switch is typically embedded in the hood latch.

The small electronic device is designed to detect whether the hood is open or shut and is an important part of the car’s alarm system – if it is broken, loose or dirty it can send false readings to the car’s computer thus triggering the alarm.

  • Pop the hood and locate the hood switch.
  • Check for any obvious damage, rust or loose connections.
  • Give the hood switch a clean too (use contact cleaner), as dirt and grime can cause issues.
  • You can test the switch with a continuity tester.

If you are well-versed mechanically, you can buy a new hood switch online and replace it yourself. Otherwise, we’d advise visiting your local mechanic.

On, owners shared the following:

“The bonnet switch can sometimes cause this…”

“My bonnet switch was faulty when this happened to me.”

2. Malfunctioning Door Switches

Faulty door switches (including the rear hatch) are another common cause of random alarms on the S2000, similar to the hood switch, these switches monitor the open/closed status of the door – if damaged, faulty or dirty they can send false readings thereby triggering the alarm.

Door switches are a common point of failure as they are subject to wear and tear due to the doors being continually opened/closed/slammed etc.

The door latches and door switches can get dirty too which can cause issues, so the first thing you should do is give all door latches a good clean and spray some WD-40 on the latch and work it in to see if that helps.

Also check the wiring leading from the body into the door for any signs of damage, it should be in a flexible hose on the hinge side of the door.

If you suspect the alarm issues are linked to the door switch, ask your dealer to run a diagnostic test to try and pinpoint the fault.

One owner shared this on

“I’m sure it’s the boot sensor that causes it. I think I finally got it to shut up by arming it with the boot open, but can’t be sure.”

Over at, one owner had this to say:

“Close the doors/hood/trunk. Lock the car and unlock the car with the key in the driver’s side door. Get in and start it. This should work if alarm is functioning normally.”

3. Drained 12V Battery

A faulty or weakened car battery causes a variety of problems, including accidentally triggering the S2000 alarm.

The best thing to do is take your S2000 for a battery health check, these are usually quite inexpensive or sometimes free such as at AutoZone.

Or you can test it yourself with a multimeter (see the guide at the end of this article).

A healthy 12V battery should be about 12.6 to 12.8 volts while a weakened battery reads below 12 volts.

One owner on S2KI suggested the following:

“This can be the symptom of a low battery. You might want to check that…”

4. Loose or Bad 12V Battery Connections

Loose or bad 12V battery connections can cause a number of problems, including triggering the alarm of your S2000.

A bad connection can be caused by dirt or gunk buildup.

The terminals may have come loose from driving and vibrations etc.

Make sure the engine is off before doing any work on the battery.

  1. Inspect the battery and look for any signs of damage, dirt build-up, rust, or corrosion.
  2. Disconnect the battery and loosen the nuts on the clamps using a wrench.
  3. Remove the negative clamp, marked with a “-” first.
  4. Clean the terminals with a toothbrush dipped in a mix of baking soda and water, rinse with distilled water and dry with a cloth.

Reconnect the battery, ensuring tight connections.

On the r/S2000 subreddit, one owner provided this tip:

“Something that unpredictable sounds like there might be a short somewhere. Also, it couldn’t hurt to pull the positive lead off the car battery for a minute or two and then reinstall it, might reset whatever is freaking out.”

8. Faulty Key Fob

Another reported cause of nuisance alarms on the S2000 is a faulty key fob.

If you have 2 remotes, try taking the battery out of one and use the other for a while.

If the alarm problems persist, and you have tried cleaning the inside of the fob(s) and changing the battery, the best thing to do is speak with your dealer.

This was argued by one owner on

“If the alarm is continuing to go off then it’s not disarming properly or is continuing to arm itself and that’s not to do with the boot sensor. Sounds more like a fault with either the fob or the main alarm unit.”

Another owner suggested this:

“Use your key to lock and unlock your driver door, this may disable the alarm…”

7. Key Fob Running on Low Battery

A common cause of mysterious alarms on the S2000 is a low key fob battery. Similarly, if the fob is dirty or dusty this can also cause alarm issues.

Give the inside of your fob a clean and replace the battery to eliminate this possible cause. It’s worth spending a bit extra for a good brand of battery.

  • To open your key fob, stick your prying tool into the slit or gap between the two halves of the outer casing and gently apply upward pressure to pop open the device.
  • Remove the battery.
  • Give the key fob a good clean to remove any dirt or fluff – a cotton swab and some rubbing alcohol should do the trick.
  • Check for damage, rust or loose connection (you may need a new key fob depending on what you find).
  • Be sure to insert the new battery facing the right way up.
  • Assemble the outer casing of your key fob by clamping them back together.

9. Defective Keyless Entry Module

A known problem with certain Honda models (in the early 2000s) is a damaged/defective keyless entry module.

The best way to address this problem is to have your unit checked by your local dealer or trusted auto mechanic.

This is what we found on

“Turns out one of my fuse for the keyless door lock control unit is out…”

10. Incorrectly Installed Aftermarket Alarm

An incorrectly installed or faulty aftermarket alarm system is a common cause of nuisance alarms.

Aftermarket alarms are typically far more complex than any factory-installed equipment which makes them more prone to issues.

They may also have been installed by incompetent individuals.

If you are experiencing issues with an aftermarket alarm, the best thing to do is speak with a reputable auto electrician.

We found these comments by a couple of owners on the r/S2000 subreddit:

“That definitely is not what happens. Someone messed with the wiring it seems. Does it have an aftermarket alarm or a factory alarm installed by the dealership? I know my factory alarm that was installed by the dealership was replaced by the previous owner because it was acting up but not sure how.”

“You’ll need to remove the aftermarket alarm system.”

9. Wind and Vibration

The Honda S2000’s alarm sensors are quite sensitive. Excessive wind or vibration can trip the alarm quite easily, according to reports online.

To deal with the wind, make sure all doors and windows are shut tight. 

As for the vibration, keep your S2000 away from roads or highways when parked.

One owner on S2KI had this to say:

“We had exactly the same problem as ours. Basically it is the wind. Close any air vents when parking because the wind can still blow up disturbing things inside the car…”

5. Water Leakage

Water leaking into the latches and sensors is quite common for owners of the S2000. It is essentially a design flaw that can trigger the vehicle’s alarm.

While the quick fix is to wipe down vulnerable areas around your latches and switches, it would be much better to consult with auto mechanics to find a long-term solution (such as adding additional seals or rubber linings).

9. Rust and Corrosion on Door and Hood Latches

Rust and corrosion can also damage the latches and switches, which may trick the sensors into detecting that a door or the front hood is open.

If your car is frequently exposed to moisture or other external elements, then you should routinely inspect critical areas of your vehicle for any sign of rust or corrosion. 

11. Damaged Wiring

Damaged electrical wiring can cause a wide range of problems, it can often be tricky to pinpoint too and you may need to have an auto electrician run some diagnostic tests.

12. Animals Climbing On The Vehicle

If your alarm has been set off in the middle of the night, it may have been by an animal climbing on the car.

States such as Illinois, Indiana, Iowa, Texas, Wisconsin, and Carolina have large wild raccoon populations. 

Have a look for footprints on the hood and the roof. 

If you have a CCTV system, examine the footage. These animals usually appear during the night. 

13. Not Closing Doors, Hood, or Trunk Properly

Something as simple as not properly closing the doors, hood, or trunk will inevitably trigger the alarm.

Make sure to check if you have closed every point of entry of your vehicle to avoid accidentally tripping your S2000’s alarm. 

Alternative Suggestions

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.

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.

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 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 for no money as they plan to make money for the repair of your vehicle.

If your unit is still under warranty then they should fix and resolve the issue for free.

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.



  • Ian Sawyer

    Growing up with a father who was a mechanic I had an appreciation for cars and motorcycles from an early age. I shared my first bike with my brother that had little more than a 40cc engine but it opened up a world of excitement for me, I was hooked. As I grew older I progressed onto bigger bikes and...