CarMD Vehicle Code Reader Review

We use affiliate links. If you buy something through the links on this page, we may earn a commission at no cost to you. Learn more.


Idiot lights. Hate them, hate them, hate them! Especially the &^%$*# “Check Engine Light”. Did you know that the Check Engine Light can come on just because the gas cap is loose? Who’s brilliant idea was it to put a light on the dashboard that can come on for everything from a major engine emergency to a loose gas cap?

Enter CarMD. This is a small, easy to use device that can do quick or in-depth readings of why that light is on.CarMD comes with the reader, a USB cable, the CD, quick start guide, and a nice embroidered nylon pouch. (Do you tend to judge a product by things like the quality of the pouch or CD label? I sure do. Not always a fair thing to do, but this is one nice pouch!)

Using the tool and the software is truly ‘easy peasy’. Plug the device into your 1996 or newer car (and the website tells you exactly where the port is for your car), turn you car’s electrical system on within 10 seconds of plugging the unit it, and wait for it to chirp four times.

The CarMD Reader
The CarMD Reader

The ‘red/yellow/green’ LEDs on the front of the reader will light up to tell you if your car would likely pass, possibly pass, or probably fail an emissions test.

Create an on-line account (CD or downloaded software) and plug the reader into a USB port with the included cable to get a detailed account of what the codes mean, even to estimated repair costs in some cases.

CarMD on-line
CarMD on-line

I tried it on one of our cars, and a car in a company fleet. My car got a green light and the company cars got a yellow. The report was quite detailed for the two codes listed under the yellow light issue- it did not pinpoint ONE cause, but rather gave an unweighted list of what it could be.  For example, one code, P0135, had this name: “HO2S-11 (Bank 1 Sensor 1) Heater Circuit Malfunction”, gave us these conditions: “DTC P0101-P0103, P0106-P0108, P0112, P0113, P0116-P0118, P0121-P0123, P0125, P0128, P0201-P0206, P0410, P0440, P0442, P0443, P0446, P0449 and P1441 not set, IAT and ECT sensors with 11ºF of each other at startup, MAF sensor less than 17-20 g/sec, HO2S signal within 100 mv of bias voltage at startup, and the PCM detected the HO2S signal remained within 150 mv of bias voltage (450 mv) for 50-80 seconds (depends on ECT and MAF at startup).” and these possible causes:

  • HO2S heater ground circuit is open or has high resistance
  • HO2S heater power circuit is open (test O2S fuse in fuse block)
  • HO2S heater element is damaged or has failed
  • PCM has failed

The fleet manager said this was consistent with a bad O2 sensor (or O2S), which was a suspected problem with this vehicle. It is important to note that the CarMD does not even claim to find everything that might be wrong with your car. I know my car has problems with a couple of the electrical systems, but there was no indication of that on the report. CarMD, like most of the ‘plug-in diagnostic tools’, mostly focuses on emissions-related issues.

CarMD comments that the tool would be useful when buying or selling cars, preparing for trips, etc. It would also be useful for a small fleet manager, etc. except that it only manages three vehicles and up to six reports a month per CarMD tool (in other words, they do not offer extensions, etc.)

As a potential car buyer you need to remember the limitations of the tool- it does not check everything, or replace the usefulness of things like CarFAX reports or good mechanical look-overs, or tell you to do routine maintenance, or offer advice on improving mileage.  It also does not reset any codes or clear the idiot light itself- you still need the mechanic for that.

The company itself helps overcome some of these things- they offer useful forms and checklists, advice, phone support if you cannot plug into a computer (such as in a car lot), and more. I am quite impressed with their on-line and other support. They do not charge for looking up codes, there is not a subscription fee or anything, and they seriously seem to be trying to be helpful to us plain consumers. Very refreshing!

Bottom line- for under $100, this is a well-made, easy-to-use, user friendly device that does just what it is supposed to and does it nicely.


Product Information

  • Easy to use
  • Great company support
  • Nice pouch (the little details are important!)
  • Does not check everything
  • Does not clear old codes from the car

30 thoughts on “CarMD Vehicle Code Reader Review”

  1. Gadgeteer Comment Policy - Please read before commenting
  2. Received my CarMD yesterday and returned it today. The product is well made, good support and classy Website, but I was very disappointed to find after reading the instruction manual that you can only have three (3) vehicles assigned to the device. Also you have to enter the VIN number for each vehicle.

    Beware, not a straight forward return policy.

    Return / Refund Policy:

    It is important to CarMD that you are satisfied with your product. However, CarMD is such a valuable tool that it can easily pay for itself in just one use by helping you save time and money on automotive repair costs. Thus, our return policy is as follows*:

    * Replacement – If the product you receive is defective, Corp. will replace the unit and pay all shipping & handling charges, provided it is within the one-year warranty period.
    * Refund (less 15% restocking fee) – If you return an unused product within 60 days of original purchase, Corp. will issue a refund (less 15% restocking fee and shipping & handling charges).

    In order to receive your full refund, complete the return request form. The product must be returned in original packaging with all items in good condition within 60 days of original purchase. If the returned product is damaged, visibly used or missing parts, we will only issue a partial refund (less S&H charges).
    * 50% Refund – If the CarMD tester has been used with a registered diagnostic report setup and run on the website (less S&H).

    * Please note: Return policy privileges apply to direct and 888.MyCarMD phone purchases only. Policy does not apply to purchases made at retail or other third-party locations. In the event you purchased your CarMD product from another party, please see their return policy or return back to store where purchased.

    For not much more money you can buy a real scanner, that cancels codes, doesn’t have to be connected to the internet to view info. If bought through, a much simpler and better return policy.

    CarMD does have its place, but not for anyone really serious about engine diagnostics.

  3. do i have this correct?, read your info on the web page, if i understand if my mercedes benz has the check engine light on and it ststes “check engine electronics” and i plug in the “car-md”it will not clear the dash warning lights, correct?.will it tell me the problem? my question stems from ,i took my 96 e320 to the shop with both check engine light and check engine electronics…which turned out to be the #1 plug mis-fired at start -up…he suggested a tune-up and reset….with check engine electronics light it “blocked-out” my digital odemeter and with nothing “wrong” would it of “reset” dash so odometer or left for shop to read and clear at their rates…thanks

  4. As stated in the review- it DOES NOT reset or clear anything- it is only a code reader. It will tell you what error it found and what it means- although the info is generally more meaningful to a trained mechanic than to you or me.

  5. “It is important to note that the CarMD does not even claim to find everything that might be wrong with your car. I know my car has problems with a couple of the electrical systems, but there was no indication of that on the report. CarMD, like most of the ‘plug-in diagnostic tools’, mostly focuses on emissions-related issues.”

    That’s what the OBD-II is really for. There are some vehicles where other data runs over the CANBus (2001+ GM’s for example) where other info such as key reminder, headlight on reminder, door lock control, OEM alarm control, etc is accessible via the OBD-II. It’s not so much a limitation of the device as it is the OBD-II port isn’t designed for those systems.

  6. It’s also important to note that a lot of obd2 and even obd1 systems which carMD doesn’t support, will display the same info on your dashboard, for example chrysler, dodge and jeep vehicles use a key trick, turn the ignition on and off 5 times then on obd1 systems the check engine light will flash a code, on odb2 systems it will give you what’s caled a p code. P followed by four numbers on the dash ( the same code the carMD will give you ), you can look up the codes on google, or buy a haynes manual which have a lot of useful info on everything that has to do with your specific vehicle.

    Some vehiles have a different obd system, for example older gm’s from about 82′ have the same 16 pin diagnostic connector, but in most cases you can use a paper clip to diagnose your problems, attach a paper clip from pin A to pin B on the 16 pin connector turn the ignition on without starting the engine, and it will flash a code, and CarMD would not be able to scan those systems.

    This is not really a new concept, you can go to an autoparts store and buy a scantool maybe for less, or a better one for about the same price.

    Like everybody else is saying it won’t diagnose everything, and I wouldn’t base buying a car on a simple scan. It’ll only diagnose problems that cause the check engine light come on, for example if my car had a blown head gasket, or cracked engine block, I might plug my carMD in, get a green light and I know I’d be good to go right?

  7. @Margie- If you can gt a free testing, then there is not a lot of benefit I know of.

    @Garfield- You’d have to contact CarMD for help. Sorry!

  8. I purchased the Car MD two weeks ago after reading about it’s Edison Award win. My intent was to give it to my father as a Father’s Day Gift. But I cracked it open 2 days ago for a friend whose Check Engine light went on. It was so easy to use and so empowering for 2 women to be able to diagnose a car issue. As it turned out her gas cap was not on tight enough and it caused the light to come on – who knew??? It saved her a trip to the dealer and convinced me to buy another Car MD for myself. So cool!!!

  9. Save you money Oreilly’s Auto parts Store will scan you car for free with a similar tool. The only way to really be able to work on your own is to invest $5000 to $6000 on a good scan tool. All a code read does is give engine codes out one module. There are still 10 to 20 other computer modules on you car that Car MD does not see. Some cases these other modules will throw soft codes which a code reader will not find, but a Shop Scanner will find. Some of these soft codes that hidden will cause the car not to pass emissions either and your Car MD will not see that. How do I know this stuff I work on 2005 and newer cars at work everyday. I’m professional technician with eight of experience on cars. I get as much time as I need to fix cars. I’m not a flat rate technician. So because of that having up to date scan tool that is design for shop used I know this stuff. Remember schucks and Oreilly’s part store do the same as Car MD for free. thanks for reading.

  10. Saved me about $250 the first time I used it.

    My dad bought me ones of these awhile back after hearing about it winning the edison award but I never had a chance to use it until recently when my engine light turned on. It took me about two tries to get a proper read (I didn’t read the manual) and was about to call it quits when it finished. After plugging it into my computer it told me what was wrong and gave me the estimated costs for repairs (cost of parts and labor).

    Whenever I went into the autoshop I usually hoped they would be honest with me rather than try to scare me into paying for something that didn’t need repairs/fixing. But this time, I knew exactly what I wanted fixed and they gave me an estimate they were sure about.

    I compared it to the price that I had printed out and counter offered – at first they wouldn’t budge, but eventually someone who could make those types of decisions gave me a discount that ended up saving me about $250, which made the final repair cost less than the carmd estimate.

    I don’t know much about cars and would usually believe in whatever the mechanics told me but this gave me a newfound confidence when coming in for repairs.

    1. Richard Clarence Ruggieri

      Wow! you actually counter-offered for the repair? Thats awesome! Very rare for any kind of repair facility to discount a repair, whether it be cars or anything else.

  11. This thing is basically useless unless you live far away from society or cant run you car. Any Discount Auto Parts or Autozone will do this for free. I suppose its possible that these are not nationwide stores but I also believe that your local parts shop would do it for you considering the rest do.

  12. Most people on this website dont know anything about cars or what they are talking about….The CardMD and code readers at the parts stores can only read PCM (Powertrain Control Module) codes which are the ones that are engine related…..You can have codes checked for free at parts stores…..But even with codes and CarMD’s help they can only tell you possible causes and alot of the times things can be overlooked since there is generic answers…..For a person that knows nothing about cars this might be somewhat useful…..For a person trying to fix a car by a innovatia scantool from walmart for $100 and you will be better off…..Above Ron says “It’s not so much a limitation of the device as it is the OBD-II port isn’t designed for those systems.”….He doesnt know what he is talking about….All systems are accessed through the obd port……Listen to people who post info on forums then you are a fool….I laugh everyday reading rediculous posts people say acting like they know how to fix things……Be smart, pay someone who knows what they are talking about.

  13. youknow they say you have a problem with your car and the car md say`s it cost with a labor and stuff like 200 buks then you gotoo auto place to get it fix and he say`s well it`s gonna cost 800buks what do you do sho`m the car md paperwork he`s gonna laugh in your face, tell youl it`s 800buks or go somwhere else.
    and you gott t o remember one thing these mechanics know pretty much what they are doing so they charge but then i get a warranty if anything goes wrong you bring it back.maybe that car md is a good thing if you can do most reapirs your self well i guess if the gas cap is too loose .

  14. um – anyone can already do this without a device. You turn your ignition on and off 3 times and a code comes up. then simply look the code up on the internet and voila . EVERY mechanic knows this and any REPUTABLE mechanic will diagnose your car for free just as easy as this gadget.

  15. A couple of places might charge and then credit you. Just know this; you take your car in. They put it on diagnose machine a lot like these ones and also they read codes. They charge you 100.00 for diagnose check. Fix it. charge another 100.00 to make sure it’s fixed. If not, they’ll keep charging you until the car is fixed. We paid 300.00 plus the parts and labor because my husband didn’t try to understand what he was suppose to do. I told him and he still neglect to check the other o2 sensors because nobody could tell him which bank he was suppose to change. Kind of his fault though. He could easily just checked them all. But expect a big fee if the dealer or independent does it. Expect to find it difficult finding out what the code is and what it means. Expect more problems if they arise. You could save money on diagnose fees and labor if you know what you’re doing.

  16. Carmd is a scam product it only reads codes if codes are stored in the pcm example a p0301 is 1 cylinder missfire the cause can be a bad spark plug, spark plug wire, ignition coil. Clogged fuel injector,leaking head gasket, oil seal,short in the wiring I can continue to go on with more causes of this one code simple enough its false advertising and you can go to ant auto zone advanced auto midas and many other local auto stores and will give you the code thats coming up bottom line a check engine light code is just a starting point that’s all it is I’m sick of companies making things up to sell a product that is worthless recalls on your car simply call the dealer with your vin# and they will tell you if you have any open recalls or tsb”technical service bulletins” I’m so aggravated I’m contacting my attorney and going to start a class action suit for false advertising

  17. Buyer Beware!!! CarMD cannot erase codes, you can only set up 3 cars total and that’s it. If you want to set up any additional cars you must pay them $15.00 for each additional car. What a scam!!! I can buy plenty of other OBD2 readers on the market that do more than this reader does and don’t have to pay extra for more than 3 cars. RIP OFF!!!

    They wouldn’t even let me return it…. poor customer service! They even count shipping time in your 30 day return policy.

    Just go to Auto Zone and they’ll do this same check for FREE!

  18. CarMD works the first two times for me on my Nissan Altima 2005 but when my Isuzu Rodeo 1998 Engine Light came on, it shows Code P1441 suggesting to replace the Air Purge Valve which cost $150.00 it works for one month then the Check Engine light came on again, I requested this part to be replaced from the dealer, they did, re-installed again, one month after the Check Engine light came on again, at this point I took my SUV to my mechanic, after he used his professional scanner told me that I need to replace the gas cap, I did and it’s been working ok since then.
    I called CarMD to see if I can get any refund for this part, they have on records that I check my car twice and the same code came up, I have my receipts of the part, the replacement form for this part and the receipt of the gas cap but they insist the CarMD diagnostic was ok.
    This scanner do not have a reset check engine light feature and you are limited to use it only in three cars, at this point I’m disappointed to have this unit. I will purchase another one from a local auto parts.
    My suggestion; go to any auto part and buy a unit without limitations like this one.

Leave a Comment

Your email address will not be published. Required fields are marked *