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How do I use an engine code reader?
So after reading the reply to why my check engine light was on, I got one of the computerized engine code reader things. What do I do now?
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Crack the code
Now, if it doesn’t have one or it was translated into English from Chinese by Koreans (as is often the case with lower-priced units) you might need a little help getting started. That’s okay, I have some words and lots of pictures that should help you out.
The FindersFree.com Legal Team Super Happy Fun Disclaimer: I’m not a professional mechanic and I never have been. I am a guy who does (most of) his own repair work on his cars, has built a couple race cars from the ground up, rebuilt the occasional engine… and has the scars and empty wallet to show for it. For professional advice, please talk to your mechanic.
How do I do this?
After you get your scanner (I have the Autel MaxiScan MS409), the first thing you need to do is find your OBD port. Note: If your car was made before January 1, 1996… you may not have the standard OBD port. Just fair warning.
Now, it would be nice if, in addition to having a standard connector, they were in a standard place… but since each car is built differently, they can be found in different locations. If your vehicle’s owners manual doesn’t tell you and you don’t own a service or shop manual for your car, that’s okay. Plug your make, model, and year into this form at the National OBD Clearinghouse. Failing that, try Google (“OBD port location [year make model]“) or just look around under your dash.
Step-by-step
On my car, the engine code reader port happens to be under the dashboard on the driver’s side and nicely labeled with “OBD” on the cover, as seen in picture #1. (For reference, that’s the driver’s door to the left and the clutch and brake pedals at center and the right.)
After removing the cover, we have access to the OBD port as seen in picture #2. Mine also has a little plastic plug that keeps it protected from the elements. I have already removed it in this photo.
Next, break out your code reader and make sure it’s ready to go (as seen in photo #3). If needed, plug in the cable into the reader as shown in the photo and insert any batteries required (as not shown in the photo). Readers vary by type, of course, so follow the correct procedure for your particular model.
Now go ahead and plug the other end of the cable into the OBD port as shown in photo #4. It is narrower on one side than the other, so you can’t accidentally plug it in the wrong way unless you use a hammer, or you’re the Incredible Hulk.
Once you’ve got it plugged in, powered up, and ready to go, put the key in the ignition and turn it to the “ON” position, where it would be after starting the car, notthe “ACC” which just turns on the radio. The car doesn’t have to be running in most cases, however you can capture more advanced data such as air/fuel ratios and the like, depending on the scanner. Again, consult your reader’s manual or barring that, just try both.
Since the menus for the various readers, well, vary I’m not going to share photos of my particular one to prevent confusion if you’ve got a different model. The option you want to read the codes is something like “Diagnostics” or similar. Either RTFM or just play around with it.
Once it has finished communicating with your car, it will display a summary screen looking something like the photo #6 below. It’s telling me that my check engine light (MIL, or Malfunction Indicator Lamp) is on, I have two trouble codes, the computer has not completed its readiness cycle (meaning it hasn’t finished self-testing since the last reset) and there is a “freeze frame” of engine data to view if I choose. The important part here are the codes, and I can bring them up on the next screen, like in picture #7:
“P1188″ is the code and “Fuel control (bank 1 sensor 1)” is the description of it. You can look these up online, as I mentioned in the check engine light answer, for more detail. If you’re curious, this one means that unmetered air or fuel is getting into the engine from somewhere. In most cases, a vacuum hose is loose, cracked, or missing. In my case, it’s a cracked boot between the Mass Air Flow sensor and the throttle body. If this is the kind of thing that reads like Greek to you, now is a good time to give your mechanic a call.
Final thoughts
As I’ve stated several times, your scanner’s operation may vary — but the basics I have presented here should get you in the right direction if you’re struggling with it. As always, with any automotive repair, if you don’t feel confident, please do get a professional involved. Good luck!
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