The Honda Odyssey is one of the best selling minivans on the market.
Like any other vehicle, its alarm may go off at random.
If your Odyssey keeps going off, we are here to help…
Table of Contents
Why Does My Honda Odyssey Alarm Keep Going Off?
A Honda Odyssey alarm is commonly triggered by faulty door/hood switches, 12V battery issues and key fob issues. Other reported causes include water damage, fuel door issues, aftermarket alarm issues and a faulty BCM.
1. Faulty Door Switches
Faulty door switches are a very common cause of random alarms on the Odyssey, 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.
- Speak to your dealer and ask them to run a diagnostic test to try and pinpoint the fault.
- The vehicles computer should have the data on which switch (sensor) triggered the alarm on the past few occasions.
Here is what owners had to say on odyclub.com:
“ … I was also getting a door ajar indicator on the dash and the driver’s door would randomly unlock, so I ended up replacing all 4 door switches (very inexpensive and easy to do), which has stopped that issue [nuisance alarms].”
“I was experiencing door lock issues with the front driver’s door. I replaced the door lock/latch module and that seemed to resolve both the door lock issues as well as the random alarm.”
2. Faulty Hood Switch
A faulty hood switch is a common cause of unwanted alarms on the Honda Odyssey.
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.
Have your dealer run a scan for the cars alarm history, it should show the trigger point and may point to the hood latch sensor being the culprit.
If you’re mechanically inclined you can buy a replacement hood switch online and fit it yourself or the easiest option is to have your dealer take a look.
3. Key Fob Low On Battery Or Dirty
A common cause of mysterious alarms on the Odyssey 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 swap 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.
Owners of the Odyssey have reported that their alarm would go off after locking their vehicle with the key fob (or remote).
Random alarm triggering can happen because the key fob is defective or low on battery.
4. Faulty Key Fob
Another reported cause of nuisance alarms on the Odyssey 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.
One poster on OdyClub.com shared the following tip:
“Change the battery in your fob then stand next to the driver door and operate it. Yours may just have lost its range due to old age. The fob receiver is inside the master door switch panel on the driver side. Put your fob right next to it.”
5. Weakened 12V Battery
A faulty or weakened car battery causes a variety of problems, including accidentally triggering the Odyssey alarm.
The best thing to do is take your Odyssey 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 Honda-Tech.com shared the follwoing:
“Get your battery checked. If the battery tests OK, thoroughly clean the battery terminals and clamps and inspect both cables, and carefully inspect the ground cable and connection to engine block and negative terminal to chassis…”
6. Loose or Bad 12V Battery Connections
Loose or bad 12V battery connections can cause a number of problems, including triggering the alarm of your Odyssey.
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.
- Inspect the battery and look for any signs of damage, dirt build-up, rust, or corrosion.
- Disconnect the battery and loosen the nuts on the clamps using a wrench
- Remove the negative clamp, marked with a “-” first
- Clean the terminals with a toothbrush dipped in a mix of baking soda and water, rinse with distilled water and dry with a cloth.
- Re-connect the battery, ensuring tight connections
7. Faulty Body Control Module (BCM)
A faulty body control module can cause a wide range of issues including nuisance alarms.
On other Honda models (Civic, HR-V and Pilot) the BCM has been a reported cause of nuisance alarms.
- The BCM is in charge of electrical communication from different electronic systems.
- This includes the car alarm system, lock-unlock functions, climate control etc.
If you feel that your BCM is the culprit behind random alarm activation, then book an appointment with your local dealership to have it inspected.
8. Water Leakage
A reported cause of alarm issues on Odyssey models is water leakage through the driver’s side door and into the fuse box. This was mostly reported on 3rd Generation models from 2005 – 2010.
As you probably know, water and electronics don’t go well together and if you have discovered a water leak then its probably best to speak to your dealer.
Here’s what one owner had to say on OdyClub.com:
“My 2008 Odyssey EX-L has been leaking when raining on the driver’s side for a long time. The water was coming out from the square airbag compartment on the driver’s side. A few days ago my alarm went off in the middle of the night and my key fob would unlock the vehicle but it would not lock the vehicle…”
These owners on OdyClub.com shared advice as to how to deal with the water leakage/alarm issue, as mentioned below:
- “Very common issue as I’m sure you’ve discovered.
- In the near-term, to stop the alarm from going off you can insert a jumper wire in the hood latch switch harness connector.
- Doing this will fool the alarm system to think your hood is always open thus preventing the alarm system from activating.”
- “Open the fuse box cover, and pull the actual kick panel away from the rug.
- I inserted the round end of a hair dryer (low heat position) into where the kick panel was pulled away.
- Let it run for a couple hours. I also stuffed paper towels behind the kick panel and above the fuse box.
- Also, be ready for the no charge light on the dashboard to show up, that happened after I cured the alarm issue.
- Turns out I was charging properly even when the light was on. I dried some more, and the problem hasn’t returned.”
The owner reported back after fixing the issue:
“I just want to let everyone know that I sealed the leaks that were letting water In, used the hair dryer to dry out the fuse box, and everything is working great! Thank you!”
“I sealed both the seams under the roof racks with black RTV and I also sealed the seams on the rear hatch with clear silicone caulk and so far no more leaks. We have also had a lot of rain recently, and the repair seems to be holding up.”
9. Fuel Door Connection Issues
Odyssey nuisance alarms have been traced to the sliding door and how it electrically interconnects to the fuel door. This has been reported mostly on 2005 – 2010 models.
If the alarm is going off whilst driving then then this is certainly something to look into, although you will need to be mechanically inclined to carry out the fix – which is either a new door switch or working on the fuel door connections.
“The driver’s sliding door locks when you open the fuel filler door. Sometimes the latch/switch breaks.”
“Update! Gas cap was messing with the alarm. We messed around with the gas cap connections to get the sliding door open, messed around with the unlock a couple of times and now the alarm is gone!”
10. Unlocking The Vehicle With The Key Fob
Some owners have reported alarm issues when manually unlocking the vehicle with the key (as opposed to using the key fob).
“Last night my son unlocked the driver’s door with the key rather than the fob/remote. He then opened the passenger door with the driver’s door UNLOCK switch. We both got in the car and fastened our seat belts, when I noticed the flashing red light on the dash. Before I could comment that the light should not be on, he started the car. Immediately, the horn started honking and flashers started flashing.” – odyclub.com
This has been reported on other makes and models of vehicle and isn’t exclusive to the Odyssey.
The simple solution is to always use your key fob.
11. Improperly Installed Aftermarket Alarm System
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.
12. 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.
13. 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.
Have a look for footprints on the hood and the roof.
14. Not Closing Doors, Hood or Trunk Properly
Sometimes a false alarm can be caused simply by not shutting a door properly, including the hood and trunk.
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.
Hood Switch Trick
One owner on odyclub.com shared the following advice for circumventing nuisance alarms:
“I had a random alarm going off. I ended up jumpering the hood latch switch connector (with a small piece of wire) to fool the alarm system to think that the hood is open all the time, thus preventing the alarm system from activating. This stopped the alarm from 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.
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.