So you were driving down the road the other day and saw a car or truck pulled over to the side of the road with its hood open and thought, Hmm, I wonder if they are broken down? The truth is that having the hood open on your car can signal several things and doesn’t always mean you are broken down. Here’s the scoop.

A driver may open the hood on their car to signal for help

Leaving your car’s hood open is often a signal that you are broken down–and might need assistance. A driver who parks their car in a breakdown lane and leaves the hood open is often signaling highway patrol or roadside assistance drivers that they need help.

If your vehicle is having engine trouble and you want to inspect the engine, you’ll have to open the hood. For this reason, most police cruisers and tow trucks will assume that a vehicle with its hood up is in some kind of trouble. If a motorist is out of cell service and needs help, they may be able to use this assumption to their advantage: one strategy is to leave their hood up and hope someone stops to see if they can help.

A driver may leave their hood open to telegraph their intentions

If a car stops somewhere besides a highway’s breakdown lane, passing motorists may not assume they are having engine trouble. Imagine a rural place where other cars stop to go hunting or hiking. In this case, leaving your car’s hood open telegraphs something very different than “help, I’m broken down.” It says, “I’m not trespassing.”

If you are in a rural area, having car trouble, and call roadside assistance, you may get sick of the number of people who stop to check on you. Some may ask if you need help, but others may want to know what you are doing parked where you are. Perhaps they are land owners or other stakeholders trying to prevent trespassing. One way to signal your intentions is to leave your hood up so at least they know you are stopped for car trouble.

There are multiple reasons to leave your car’s hood open

If you see an older car parked with its hood open on a hot day, it may not be signalling for help at all. In this case, the driver may simply have an overheating engine and be waiting for the engine to cool down. Let’s say the engine is running at 200 degrees fahrenheit, even on a 90-degree day, letting the engine cool to the same temperature as the ambient air will allow you to drive safely. If you open your car’s hood, the engine will cool quicker.

If you see a car parked on a residential street with its hood open, there may be an even more surprising reason why. Reddit user Spirt Dust noticed multiple residents of Tucson, Arizona, parking their vehicles and leaving the hoods up for long periods of time.

User Foyles War explained the local situation, “Pack rats. They get under the hood and eat the wiring. Very, very expensive. Leaving the hood up and an outside light on makes it less of an appealing cave. I’ve had it happen twice – once with $3k to rewire, once, I drove off with the packrat under the hood and fried it – not a nice smell…”

Next, find out what a white towel or bag on a broken-down car means.