When funky lights pop up on your dashboard, whether they say “Check Engine,” or “Brake,” it’s enough to freak out any wary driver. These lights mean that something bad is going on, and while every once in a while you’re lucky enough to have that “bad” thing be as minor as a faulty gas cap… well, usually, the problem is a lot more expensive.
While it would certainly be nice if your dashboard lit up with clear warnings like “Hey, it’s time to refill your coolant!,” that’s not quite how it is, and unfortunately, you aren’t given a lot of information. On the other hand, the good news is that all these car alerts have been standardized for a couple decades, thanks to a little thing called OBD-II. Once you understand the basics of OBD-II, you’ll have a big leg up in understanding what, exactly, is going on with your car, and knowledge is power.
Okay, so what is OBD-II? Why do car-makers have to use such weird encoded phrases in the first place?
Well, first of all, take a look at your car. Any car, don’t worry about the make and model. Down beneath the steering wheel, usually on the left side, you’ll find a little square plug-in spot. That’s what we’re talking about—but the back story is more interesting than you might expect.
You probably figured out that OBD is an acronym, standing for “On-Board Diagnostics.” Back in the 1970s, the EPA started requiring automobiles to abide by certain emission standards, because smog was getting so bad. So, carmakers began using electronically controlled fuel feed and ignition systems. These electronic sensors measured engine performance, and then adjusted functions in such a way that pollution was minimized. There was another nice perk to the whole thing, though: these sensors also could tell you that something was wrong with the car, with electronic functions, before the car just broke down, or the engine started smoking, or what have you.
However, none of these alerts were standardized for quite some time, leading to different automobiles having different alert methods. That all changed in 1996, when OBD-II was made mandatory for all cars manufactured or sold within the United States, meaning that all of the functions—for example, a Check Engine light—were universal, as was the plug-in accessibility. Safer cars make for safer roads. So yes, OBD-II is a good thing… and so is the Check Engine Light, as much as you might hate it.
As it happens, there’s a good chance that you’ve seen an OBD-II scanner before.
If you’ve ever had issues going on with your car that led to some dashboard lights coming on, you probably either brought the vehicle to a mechanic, or maybe to a parts store like Amazon. Generally, the first thing that these guys are going to do is bring a little held held device to your car, plug this device—which is the scanner— into that spot beneath the steering wheel, and wait. After a few minutes, a code, or maybe a few codes, will appear on the scanner, alerting them to what the problem is.
In case you thought these scanners were some sort of inaccessible tool, they’re actually easy to find at any automobile parts store, and not that expensive. However, the trouble with using a scanner yourself is simply that the codes it gives you aren’t necessarily… easy to interpret.
The codes that appear on a scanner are called DTC, or Diagnostic Trouble Codes. Before you start writing down every code and making flash cards for yourself, though, keep in mind that there are hundreds of possible codes to learn. Diagnosing a sick car is just like diagnosing a sick human. It’s complex.
If you’re using a traditional OBD scanner, the best way to proceed is to get a pen and paper, plug the scanner in, and then run it. It will list a series of codes, and you should write them down in the order in which the scanner reports them.
Like your driver’s license or your tires, the long string of numbers and letters that appears isn’t randomly chosen. It’s based on a careful sequence, a pattern, explained here by Your Mechanic, which is consistent every time. For example, the first digit in the code will always be one of the following four letters: P, B, C, or U. P codes relate to powertrain problems, B codes are body codes, C codes are about the chassis, and U codes are about network communication. The numbers following this help you to understand whether the problem is generic or manufacturer specific. You get the drill. However, actually interpreting these codes properly takes a lot of experience beneath the hood. Luckily, with today’s technology, there are some easier alternatives.
As we said before, a sick car is like a sick person. Until recently, though, what’s been lacking is a proper diagnostic tool, in order to translate these strange codes into something that a layperson can understand.
These days, though, there are OBD-II readers that are designed specifically with the average, non-car person in mind, such as the FIXD car health monitor. This sensor plugs in the same way as any OBD-II reader, but instead of spitting out funky codes, will instead give you easy to understand directions on what exactly is ailing your car. It’s a cool innovation, and you can read our FIXD review here.
In the end, though, what’s important to understand about OBD-II systems is that while they might seem daunting at first, they exist to help you, not to hinder you. OBD-II makes diagnosing car ailments into a far easier enterprise than it was previously, lowers emissions, and has generally made for a cleaner, less stressful world. So next time you get a Check Engine light, know that as distressing as it might be, it’s actually a good thing that your car has the ability to tell you something is wrong.