Two problems related to horn assembly have been reported for the 2008 Honda Odyssey. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2008 Honda Odyssey based on all problems reported for the 2008 Odyssey.
The alarm went on at around 2am and kept on going. Switched if off using key fob. Checked all doors and windows and nothing was open. After about ten minutes it started going off again by itself. As I was watching at that time, there was no reason for the alarm to go off. The same thing repeated over several nights and this became an issue for us and neighbor's. From then on, I have started taking out the horn fuse when parking. As this happened a few months ago, I have given an approximate date below. I am having this checked by a dealer, though I doubt they can find the cause as this occurs randomly. This has however become a major headache.
The car alarm horn going off for no reason at 2 am in the morning. Hit the lock button on the remote and alarm stopped. When daylight, found driver side door was not locked but all the other doors were locked. Then another incident in a week, 4 am the car alarm horn going again. Shut it off with remote. Within 5 minutes the car alarm horn went off again. Shut it off with remote and went outside, opened the driver side door with key. Then locked all the doors with manual switch on driver side door panel and closed the driver side door. The vehicle, while a 2008 model has less than 27,000 miles. This should be a recall for Honda automobiles in general from reading complaints.