Honda Odyssey Car Keys Work in Civic Car

My sister unknowingly grabbed her Honda Odyssey car key and used it to start and drive her Honda Civic. She didn’t realize what she’d done until she had trouble taking the key out of the ignition after driving the Civic. Now we’re wondering about these car keys and security. Can anybody use their Honda keys to drive someone else’s car?

Interesting, I’d love to see someone’s input on this.

I have a theory but whats the years of the vehicles? They may have same cylinder for ignition, doubt it but its a theory.

There are so many combinations for a car key. So I believe there is a repetition rate, might be every 100 or 1000 or 10000. But still possible to grab a key from any Honda and be able to open the doors of another similar year range Honda.
My dad has poor vision and couple of times he had opened up another car (same make and color, parked in the same neighborhood) and only when inside he realizes that it is not his car.

@galant Indeed. I purchased new cylinders for my GM, sure enough the new keys matched the stocks that were in it, didn’t have to replace the drivers side (didn’t realize this until after passengers was changed out).

I had a rental car a few years ago. After dinner at a loca restaurant, I unlocked the door (with the key) to my car and tried to start the engine. The key didn’t work. It turned out that it wasn’t my car, but one that someone else on our team rented. I don’t think any Honda key will work on any other Honda, but there are not an infinite number of combinations; some dictation is necessary.

I think you had a combination of a close match and a worn ignition on the older car. I can’t speak for Honda, but some manufacturers may have more tumblers in the door locks than in the ignition locks, probably more to make a more compact lock for the steering column than anything else. I know glove compartment locks are often this way. Eg. a door lock may have 5 discs while an ignition lock has 4. This means that you have a lot more chances for a key from another car to start yours, while it may not open your doors, due to one extra matching key cut being necessary for the extra tumbler in the door lock.

I have actually seen this on an old Russwin double-cylinder (house) deadbolt, where the inside cylinder was built into the horseshoe-shaped deadbolt unit, and only had 3 pins, using the 3 cuts closest to the key’s head, while the outside cylinder had 5 pins. The unused length of the key stuck out the back of the cylinder inside the unit. Some master key systems that contain a large number of locks with several levels of master keying and desired access groups (like for a large facility or campus for example) may also use this system, with some locks having all pins, some having one less, and some missing a pin in different positions in the cylinder to accommodate the convoluted key schedule, though these type of systems typically have at least 6 pins for greater security, and may have the entire system duplicated at least once, but with more than one keyway–so that two keys can have identical cuts, but would not fit into cylinders meant for each other.

I once almost started work on the wrong car.

I grabbed the key off of the pegboard and looked for the car in the back lot.

I unlocked it, started it and drove to my workbay.

I realized my mistake when I popped the hood and it had the wrong engine!

Years ago, my fellow teenager friends, to avoid the boring parts, would go out into the church parking lot – when everybody else was inside attending the church meeting – we’d go outside and try out our own car keys on all the cars in the parking lot. We could usually open the locked door and start at least one of the 40 or so cars or trucks in the parking lot.

When my father bought a new Ford Econoline van in 1980, he discovered that his key fit his brother’s 1962ish Ford pickup and vice versa. Each key was an exact match of the other. It’s rare to find two car keys that are an exact match. The odds are pretty low, but it does happen. There are only so many key patterns out there for each type of key, so there has to be some repetition.

I had a 1950 Chevrolet pickup truck and my mechanic lost the key. However, he gave me a key that he said would work the locks on many GM products of that vintage. It didn’t work smoothly, but it would operate the ignition switch on my truck. The switch only had two positions, Off and On. The starter was operated by depressing a pedal on the floor. The starter would operate whether the ignition switch was either On or Off, but the engine wouldn’t start in the Off position. My key eventually turned up and I gave back the “master” key.

Years ago we had about a dozen General Motors car keys of varying shapes. There was almost no GM vehicle we couldn’t get into (although some did require a bit of juggling, or pulling the key out a bit as you continually tried to turn the key).

Then in 1967, GM changed their key style across their whole line. Pre-1967 keys would not fit into locks for 1967 and beyond.

Here is a somewhat interesting article on the evolution of auto lock technology: