On-Board Diagnostic Tools: For When You Want to Throttle Your Check Engine Light
To round out our on-the-road week, we’re taking a look into on-board diagnostic scanners, commonly known as OBDII or ODB2 readers. These tools take a look at the information readily available about your car’s mechanical and electrical systems and make it available to you. This is the same information accessed by emissions testers or by your car when it decides to illuminate the dreaded “check engine” light. We tested out three types of these devices, with different capabilities and price points: the Black & Decker AD925 Smart Scan , the ScanGauge II, and the VI Monitor OBD gauge.
I remember when the check engine lights were being phased in. My grandmother had a car that kept flashing the light. She would bring it to the mechanic and he would check it and find nothing wrong and then the light would turn off. She would leave and a few days later the light would turn on again. She did this a couple of times before the mechanic just decided to disable the annoying light and my grandmother thanked him and paid him for fixing the problem. Contrast that with today, where a car will often fail emissions when the “check engine” light is on- but even better, you now have access to the same tools that professionals use to determine the issue.
Quite a while ago, the on-board diagnostics (OBD) that triggered the “check engine” lights only tracked basic data relating to the end result of emissions. More recently, most cars in the last decade have added a thermostat monitor and a PVC system monitor in addition to more finely tuning what does and doesn’t trigger a “check engine” light. The OBD is even technically the OBD II, which has been phased in since 1996.
After working through California’s stringent emissions tests during some testing of used cars, we became interested in these devices as a way to take control of our cars and taking more proactive care of them. These diagnostic systems are really handy for emissions testing, but also to give you a better idea of what is going on under the hood! Many states will run your car through an OBD test like the one on your system, and if the OBD says it passes, it passes. So if you have such one of these tools, there shouldn’t be any surprises before emissions.
All three of the models we took a look at had slightly different uses. The Black & Decker Smart Scan had a handy manual to consult- like most readers, it simply presents an obscure error code to you and leaves it up to you to decode. It’s mostly meant as a tool for you to run a diagnostic on your car when there seem to be problems, and can be easily kept in a glove compartment for use when necessary. The manual contains a list of the most common codes and the issue underlying them, and it’s easy to check online for rarer or vehicle-specific ones.
We think it’s also an excellent device for checking on a used car you’re interested in buying, as it only takes a few seconds (though the car must be on). Since bringing along a mechanic is not always an option, this handy device can at least help inform possible problems with the vehicle. We liked that, like the other devices mentioned here, it draws power straight from your car’s OBD slot (usually below the steering wheel). Battery operation is an option when you want to look at saved data away from a car, but requires an excessive number of AA batteries. Also, saved data is erased when the Smart Scan syncs with a new vehicle, so be careful.
The ScanGauge II is a level up in capability. It’s a sophisticated trip computer, a digital gauge and a scan tool. It’s meant to be installed into your car and stay there, giving you data both in real time and over the long term. You can even look over to watch what your car is doing while driving- just be sure to watch the road!
We felt the most useful part of the ScanGauge II was telling us our miles per gallon as a real snapshot. This allows you to better understand how your actions are effecting your gas mileage, and realize things like what the sweet spot is in speed, how much more gas you burn when you accelerate a lot, and how much driving with the AC on and the windows down is actually costing you. The trip computer is also nice and far easier to use than your odometer, and allows you to see how other drivers (like your teenager) are driving, including their speed.
The ScanGauge II isn’t sexy- it’s a basic LCD screen, but fairly large and easy to read, with helpfully long cables that make it fairly easy to install. There is also a built-in backlight, which was quite handy for nighttime driving. The buttons are a bit awkward and unlabeled, but with some fumbling, you can manage to reset error codes (and thus turn off that pesky warning light should you wish).
The VI Monitor was certainly the most graphically appealing of them all. It offers basically the same functions of the ScanGauge II but in a sleeker package and with a few added features to boot. They helpfully include a list of the fault codes so if something goes wrong, you can analyze it on the spot with no need for a manual or guide. It also has a 3-axis G-sensor built in, so you can see acceleration, braking and cornering G-forces. The device can even calculate horsepower and allows you to perform performance tests for accelerating and braking- very cool stuff actually, and we found it to be reasonably accurate. 500 hours of data logging allows you to track your car or truck over quite a while as well. If that isn’t enough, you can even connect it to your computer and use their V.I.D. software to both download and compare/examine the information!
We loved the ease of use- handy dials and various screens made the information easy to absorb and understand, and the touch screen was responsive and clear. Everything is quite configurable, so you can set it up to show the data important to you. There are tons of tweaks you can do as well, and the screen is large and bright. Of course, there is a price to be paid: the VI Monitor is also the most expensive of these three by far and, unfortunately, is very very obscure. It’s currently only sold in the UK, so good luck getting your hands on it (Amazon UK does carry it). Made by the same folks behind the IO Play that we recently checked out, we hope to see this hitting our shores in the future, and perhaps encouraging car manufacturers to build-in devices like these as standard equipment. On the downside, between your radio, your GPS, and your monitor, you’re going to have a lot of screens to pay attention to.
None of the devices have to be installed permanently or require much work to setup, and in fact the Black & Decker cannot be. So, pretty much all these devices can be taken around as your own personal portable mechanic when checking out a used car. The more sophisticated pair can show you how your gas mileage improves when drafting, and the VI Monitor will even let you know the G-force you’re taking on when you hit that turn.
The Black & Decker Smart Scan is available for about $65. The ScanGauge II is available for about $170 through their site or about $160 on Amazon. The VI Monitor is available in the UK and online for UK250.
