Why Doesn't the 12v Socket in My Car Work?

Shouldn’t I be able to use my cigarette lighter to plug in 12v stuff?

All cigarette lighter sockets are also 12v sockets, which means that you should be able to plug in a cigarette lighter inverter, cell charger, or any other 12v DC accessory into any cigarette lighter socket, in any vehicle, and have it work just fine.

When a cigarette lighter socket stops working or seems to malfunction, there are a few things that can go wrong:

  • An obstruction inside the socket - This happens most often when the cigarette lighter socket is installed vertically into a center console since that orientation makes it very easy for small items to fall into the socket. Non-conductive obstructions prevent chargers from making contact, while conductive objects like coins can blow the circuit.
  • The cigarette lighter socket is blown - This just means that there's no power getting to the socket at all. The fuse could be blown, or there could be another problem with the wiring.
  • The charger itself is bad - Chargers do go bad, so you need to rule this out. The electronics inside the charger could be bad, the plug that goes into your device could be back, or the springs in the plug that goes into the cigarette lighter socket could be worn out.

How to Fix a Cigarette Lighter Socket That Doesn't Work

To get your cigarette lighter socket working again, you need to check and rule out each potential issue. Some of these steps are very easy and require no special equipment, but fully completing this type of diagnostic does require a test light or voltmeter.

Here are the basic steps to follow when your cigarette lighter stops working:

  1. Check for foreign objects inside the cigarette lighter socket - If you find anything inside the cigarette lighter socket, like food, small toys, or coins, carefully remove it. Do not reach into the socket with any metal object like a screwdriver or tweezers.

  2. Check for power and ground at the socket - This requires a test light or a voltmeter. If you have these tools and know how to use them, check for power on the center pin inside the cigarette lighter socket and ground on the interior of the barrel. If you don't find power, check the fuses. If you don't find power or ground, check the connections that plug into the cigarette lighter socket.

  3. Try plugging in a different device - If you don't have a test light or voltmeter, locate a different 12V charger or device. It's important to make sure that the device actually works, so you may want to borrow something from a friend or family member that they use regularly. If you plug it in, and it doesn't work, there probably isn't power to the socket.

  4. Try plugging in the cigarette lighter - If you still have the cigarette lighter that came with your car, plug it in and activate it by pushing in firmly. If it pops out, and the coils are red hot, there's nothing wrong with your socket. If it doesn't heat up, your socket doesn't have power.

  5. Try plugging your charger into a different socket - If your vehicle has additional accessory sockets, check to see if your charger works in them. If not, try your charger in a different vehicle. If it doesn't work in the other sockets, your charger may be bad.

Check for Foreign Objects

In a situation where nothing you plug into a 12v accessory socket works, the first thing you'll want to do is check for obstructions inside the socket. The easiest way to do this is to grab a flashlight and physically look inside the socket.

A cigarette lighter socket with a coin shorting out the circuit.

One of the most common causes of cigarette lighter and 12v accessory socket problems is when a coin falls into the socket accidentally. This can cause the socket to short circuit and blow out the fuse, but it can also prevent accessory plugs from making contact.

When non-metallic objects fall into a cigarette lighter or 12v accessory socket, you won't end up with a short circuit or blown fuse. However, the foreign object can still prevent an accessory plug from making electrical contact. That means the circuit will still be hot when you reach inside to remove the instruction, so take care not to accidentally short it out.

Check for Power

If there aren’t any obstructions in the socket, then you can proceed in one of three ways. The easiest is to simply plug in the cigarette lighter if you have it. If the lighter heats up and pops out, then the socket has power. You can also use a test light to check for power, if you have one, or examine the fuse panel to see if the cigarette lighter fuse is blown.

If your 12v socket is actually an accessory socket and not a cigarette lighter socket, then you can't test it by using the cigarette lighter. In that case, you'll have to use a test light or multimeter to actually check for power.

If the fuse isn’t blown, and the socket has power, then there may be an issue with either the socket or the accessory plug that you are trying to use with it. Cigarette lighter and 12v accessory sockets are designed with somewhat loose tolerance in mind, and the slack is taken up by spring-loaded contacts, but if contact isn’t taking place, then your accessory won’t receive power.

Dealing With a Blown Cigarette Lighter Fuse

In many cases, you will find that the cigarette lighter fuse is blown, which can be the result of a number of different issues. If you found a coin in the socket, then that is probably the end of it. If you didn’t, then you may have a short elsewhere, or you may have plugged something in, like a cigarette lighter inverter, that simply draws more amperage than the circuit is designed to handle.

Cigarette lighter circuits are often fused at 10 or 15A, which isn’t a whole lot in the grand scheme of things. So if your cigarette lighter inverter isn't specifically designed to keep current demands below that level, plugging in any number of electronics could theoretically blow your fuse and keep the inverter from working.

The easiest way to proceed from there is to replace the cigarette lighter or 12v accessory socket fuse and see what happens. If it blows immediately, you’re dealing with a short somewhere in the circuit. If you plug in the cigarette lighter and the fuse blows, then that is probably the issue. If everything is fine initially, but the fuse blows when you plug in the inverter, then the inverter is probably the culprit.

In any case, the inherent limitations of cigarette lighter inverters mean that you may end up better off with a different inverter that is hooked either directly to the battery or to the fuse panel. For more information about that, you can check out our article on how to estimate inverter requirements.

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