CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Best Scan Tool for Home Use

These things range from $20 to $6000 from what I’ve seen.

I’ve also read that some of the cheaper ones do not display all of the specific needed information from a code reading.

If one wasn’t looking to reprogram anything or do calibrations and what not, what would be a recommended budget friendly scan tool to purchase?

The scanners that can read live data are very helpful in diagnosing problems and some are priced under $100.

Free scan at an auto parts store, second scan at a dealer if needed.Dealers can perform a more comprehensive scan was my experience wit a ford

You can buy an ELM-327 adapter and use and android phone or tablet with the Torque app to pull codes and read live sensor data. I found a program for Windows, Forscan, that uses the same adapter to read ALL the modules in Ford, Lincoln, and Mercury cars and trucks. The ELM-327 adapter can be found at several online sources, like eBay and Amazon for less than $30, the Torque app is about $6, and they have a free version that is very limited, and Forscan is open-source and free.

You did not state what dollar range you meant. My personal suggestion is to buy more scanner than you think you need. I bought a simple scan reader quite a few years ago. It will read codes and erase them. Eventually, I realized I needed more.

I looked in Amazon and settled on an EQUUS 3140. When I bought it a couple years ago, I think it was under $200. I will tell you why so you know what to look for, which will almost certainly not be the same one I bought.

I got the 3140 rather than another EQUUS model, because I live in Mexico, where people drive older cars much longer. The 3140 has adapters which will connect to some pre-1996 models. Which I thought might happen because neighbors have such vehicles.

I wanted live data. That means I can monitor sensors; can see engine temperature; can see the sensors which are used to determine if the cat convertor is bad or not. I can also see values when a bank says it is not working as expected.

I can also see freeze frame, which means when the code occurred, the computer remembers the conditions under which it failed.

The 3140 also tells you which monitors are tested and which are ready to be tested.

The 3140 also claims it connects to the newer CAN systems. I don’t know because I don’t have a newer car.

As an example of live data, when I scanned the town garbage pickup for engine codes, it said engine coolant problem. The live data told me that the sensors indicated maybe 40 below zero, so that gave me a clue the failure was total, not an accuracy problem.

My view of a scanner is it will probably serve as long as you own the car you bought it for. Newer systems may make it obsolete, but it will always work on that car. As a car ages, you are more likely to need a scanner, and more likely to need more data than a simple reader gives you.

I do not suggest only EQUUS, just because that is what I bought. I am sure there are many other good scanners of other makes.

Equally as important as the correct scanner for your needs, is knowledge of OBDII. There are plenty of on-line articles on OBDII.

I had an extreme advantage in spite of not a great amount of car repair experience compared to our top guns on Car Talk. I worked for many years on high technology for military aircraft. The black boxes often had built in self-monitoring circuitry to report promptly any internal failures in the black box so the pilot would know not to trust his readings.

When I started reading about OBDII I realized the concepts were the same. A complex program which monitors a wide range of components and outputs, under stated conditions and within stated specs, then calls it a pass or a fail.

The engine computer does a lot, and does it very fast.

A given test will first make sure the system is ready for that test. If the sensors are not working, the computer may go into default mode, often called limp mode, but will not run other tests. So, you could have one test that fails thus masking other system problems because the other tests will depend upon the failed test as a pre-condition to run the later test.

A test may only be run at a certain minimum engine temperature, or outside air temperature.

I had a failure back in the Midwest last month. The heater on bank one sensor one opened up. That apparently is an instant CEL. Hot filaments usually fail at the instant they are turned on, like light bulbs. So, when we stopped at a truck stop to get souvenir post cards, the light came on the instant I started the car. I noted it as soon as we re-entered the Interstate, and stopped at the first rest stop to read the code.

It was only the heater, so after warm-up which doesn’t take that long, the injection was normal. I was able to continue the cross country trip to McAllen. The big danger of driving with a known CEL is if you get another one, you won’t know it.

Other tests may not run very often at all.

Evap pressure is a tricky one. A lot of conditions have to be met before it will even run the test at all. And, if it fails, the codes tell you almost nothing about what caused it. In the case of my Sienna, it was very intermittent, and another man on Sienna Chat swapped his canisters between his second Sienna and fixed it, so I knew what the problem was.

My point is not to supply an OBDII primer, but to explain why you need to learn about OBDII. For first timers, the concepts can be scary, and yet once you have a basic grasp of the concepts the scanner is much more useful.

As mentioned it all depends on what you want to use it for. For basic codes the android app and adapter is fine. Then you can buy a cheap reader from Harbor Freight, it has decent reviews for what it does. I think most of these would not read ABS/air bag codes.

Check out the Actron CP9575 if you haven’t already done so. I’ve been using one for years and absolutely love it. It displays freeze frame data, live engine data, internet updatable, has manufacturer specific code definitions, gives oxygen sensor readings and a few other things. It sells at Amazon for $100 bucks which seems very reasonable for the build quality and it’s capabilities.