You’ve probably heard about OBD2 readers that can diagnose your car for any problems it could be experiencing.
But sometimes these don’t offer enough information about your car’s transmission. This is why you need to purchase a transmission code reader.
What is a transmission code reader? A transmission code reader is a small tool that can spot problems with your car’s transmission before they become a real issue.
How they work is that they will scan your car for any transmission fault codes and enable you to know exactly what’s wrong with your car, while also removing error codes.
With that in mind, let’s check out the best transmission code reader on the market, along with four great alternatives so you can start monitoring your car’s transmission and take better care of it.
Contents
Best Transmission Code Reader – Reviews & Buying guide for 2021
Best Overall: LAUNCH CRP123 OBD2 Scanner
Whether you want to check your car’s O2 sensor or SRS system, you’ll be able to do so with this best transmission code reader.
You can also do much more, so let’s check out what this device has to offer and why it’s our number-one product.
Pros
- This OBD2 transmission code reader is affordable yet powerful. You can view live data streams from your car’s engine, ABS, SRS, and AT systems.
- You can go through the data in graph format, or record and print it for later viewing.
- You’ll also be able to reset codes for your transmission, engine, ABS, or SRS system.
- You’ll gain a comprehensive view of your car’s health, such as when it comes to its O2 sensors, smog levels, and more.
- If you’re unsure of what a code means, you’ll easily and quickly be able to look it up with the device lookup tool. There’s also an acronym database included, which is a bonus.
- Cars that are made in the U.S., Asia, and Europe are all compatible with this transmission code reader.
- It’s small and compact enough to fit into your bag or in your car so you can have it handy for long trips.
- It’s simple to use and comes with clear instructions, so it’s beginner-friendly.
Cons
- Some people who have purchased this scanner have reported problems with updating it.
- Others have reported issues with the scanner not reporting ABS fault codes correctly.
Runner Up: OTC Tools 3208
This OTC Tools transmission code reader helps you to achieve a comprehensive way of maintaining your car’s wellbeing. Let’s see what it has to offer.
Pros
- This transmission code reader has a live data stream that can read engine data for all cars and light trucks that were made in 1996 or later years.
- It has ABS codes as well as definitions to help you diagnose a variety of vehicles.
- Once you’ve repaired the fault in your car, you can erase the fault codes and remove the “check engine” light yourself, without having to take your car to the mechanic.
- The user manual is built to be comprehensive. You will gain pages of live data by using this code reader, with the ability to monitor various functions of your car, such as engine load, RPM, and more.
- This is a transmission code reader that’s value for money because of how it offers you more diagnostic codes than what you’ll get from cheaper code readers. It also offers specific results so you can know exactly where the problem is in your car.
Cons
- This device isn’t backlit which can make it uncomfortable to use in poor visibility conditions, such as when you’re working in a dark garage.
- It does not read ABS codes for all types of vehicles, so you might find that it’s limited when it comes to your specific car make and model.
Alternative: Autel MaxiLink ML629
This transmission code reader can give you a wealth of information about your car, from its ABS and SRS systems, to its engine and transmission. Let’s check it out!
Pros
- This code reader for transmission is versatile enough to work on all cars, light trucks, sedans, and SUVs to scan their systems and enable you to read and clear error codes, as well as turn off the “check engine” light.
- It also enables you to turn off other lights, such as MIL, SRS, ABS, engine, and transmission warning lights.
- If it feels overwhelming to have to learn what all the trouble codes mean, don’t worry. This transmission code reader has a diagnostic trouble code library that’s equipped with 7,000 definitions so you will always know what’s wrong with your car without having to first look up the error codes online.
- This code reader has a data review feature. This allows you to go back and review the information it has collected. You can also print it out for further convenience.
Cons
- Some people have complained that this transmission code reader sometimes has problems when it comes to its updates.
- Others have said that it’s not very user-friendly.
Alternative: FOXWELL NT624
This handy diagnostic device offers a range of services to make you feel like a DIY mechanic. Let’s check it out so you can see if it’s the best transmission code reader for your needs.
Pros
- This transmission code reader scanner is an upgraded scanner from the company that’s designed to be user-friendly for both beginners and professionals.
- It offers an oil reset and EPB reset, which are two features that you won’t find on many other transmission code readers on the market.
- It offers you live data that you can record, playback, and print, for the ultimate convenience.
- You can also view the live data in graph format.
- It has a variety of ways in which it will monitor your car’s systems and diagnose problems. It’s powerful enough to scan car systems such as the transmission, ABS, SRS, DME, steering wheel, wheels, and more.
- The OBD2 diagnostic features are available for over 1,000 types of cars.
- Once you’ve read the error codes, you’ll be able to use this device to clear them.
- It has an auto VIN scan feature. This enables you to quickly identify your vehicle so you can get to the bottom of what’s wrong with it.
- Since it’s already packed with the software you need to be able to use it, you can use this car code reader straight out of the box.
Cons
- Some people who have purchased this transmission code reader have reported that it doesn’t offer all the listed features, but this depends on the type of car you have. It’s always worth getting in touch with the device manufacturer before purchasing a code reader to find out for sure if it will be compatible with your car make and model.
- Since it is quite wide, you will battle to hold and use it with one hand.
Alternative: Autel OBD2 Code Reader
If you’re looking for another comprehensive diagnostic tool, this one by Autel is worth considering. But, is it right for you? Let’s see its pros and cons.
Pros
- This handy car scanning device has a slightly curved design so it’s easy to hold in your hand.
- It can access every module in your vehicle’s system. So, you can use it for everything, from scanning your car’s OBD2 to resetting the oil and EPB.
- This device will read and clear all system trouble codes, such as those for EPB, ABS, engine, and SRS.
- This is an OBD2 reader that will give you information about your car’s engine so you can monitor its wellbeing and turn off the “check engine” light.
- You’ll also gain essential information about your car’s emissions, which is sure to help your car pass its emissions test.
Cons
- You can’t use it straight out of the box because you first have to select and download the software you need from the website. The first software you purchase will be free, after which you will have to spend $10 for the software per vehicle.
- Some people who have purchased this transmission code reader have reported difficulties with using the company website to install the software.
Transmission Code Reader FAQ
Do you still have some questions about transmission code readers? Here are some important questions and answers so you can learn more about them and which one you should buy from our list of the best transmission code readers.
Can the OBD2 scanner read transmission codes?

Although we’ve seen in our list of reviews that you can find scanners that can gain a wealth of other information about your car’s engine without being limited to just the transmission system, the truth is that not all OBD2 scanners will be able to read fault codes from your car’s transmission.
If you are interested in a basic OBD2 scanning device, you will likely only be able to read and remove some engine fault codes.
So, your next question might be, “What happens if your car’s ‘check engine’ light comes on as a result of a faulty transmission?”
In that case, you will have to use a transmission code reader in order to find out what the problem is with your transmission and how to fix it.
If you are in the market for an OBD2 scanner to diagnose problems with your car, you should make sure that it will be able to read transmission codes so that you will get a more comprehensive reading from the device.
Or, purchase a transmission code reader so that you can zone into your car’s transmission specifically to see that it’s working properly.
Is there a diagnostic test for transmission?
If you suspect that your car has a problem with its transmission, your mechanic will usually be able to diagnose it in a variety of ways.
You can use an OBD2 scanner, provided that it can read transmission codes, or a transmission code reader, but there are other ways in which your mechanic will be able to run tests on the transmission.
The mechanic will have to monitor the transmission and check its individual components to find out if any of them are not working properly. If you have an older car model, this type of diagnostic test will take more time.
This is because older cars aren’t computerized, so mechanics have to rely on their own observational skills in order to diagnose transmission problems.
For example, he or she will have to listen for any strange sounds coming from the car, like popping sounds.
However, whether your car is an older or newer car model, there are other transmission-related problems that a mechanic will be able to spot, such as a burning smell, difficulty in changing the car’s gears, shaking or vibrating, leaking transmission fluid, and the “check engine” light that comes on.
In modern transmission systems, there’s less guesswork than with older cars and this also enables you or your mechanic to make use of accurate tools to find out what’s wrong with your transmission, such as a transmission code reader or OBD2 scanner that has the capability of reading the car’s transmission for any errors.
To use an OBD2 scanner to diagnose your car’s transmission, this device will have to be inserted into your car’s OBD2 port. An error code will be displayed which will alert you, or your mechanic, to the faulty part of the transmission.
The mechanic might also do a test drive with the car while the OBD2 scanner is plugged in so that it can monitor the sensor data as well as the car’s onboard Engine Control Unit (ECU).
During a transmission diagnostic test, the following things will be tested: transmission fluid levels, upshift and downshift timing, initial transmission engagement, neutral and reverse performance, 4X4 performance, parking, vibrations, passing gear, torque converter clutch engagement, vacuum and harness connections, mounts and U-joints, pan gasket, axle and shafts, fluid retention, and shift linkage and cables.
What happens if you drive with low transmission fluid?

Transmission fluid is essential to keep at the correct level for your car because it serves important functions, such as ensuring that all the parts in your car’s gearbox don’t grind when they move and allowing for smoother gear changes.
This is why if your car has slipping gears or you feel it’s more difficult to change gears than it used to be, these can point to problems with your transmission fluid.
Sometimes a leak can occur in the car’s transmission system, and this can cause your transmission fluid to not be at the right level.
If you carry on driving even though this leak is occurring, it can damage your car’s transmission, lead to very expensive repairs, and require replacements.
If you drive your car until your transmission fluid runs out, this is even more damaging to your car and it will completely shut down.
This is why it’s so important to keep your transmission fluid at the correct level for your specific car. If there’s a leak, you will need to have this seen to as soon as possible so that you prevent further damage.
There are some other signs that your transmission fluid level is too low, or you have other problems with your transmission, and which you should pay attention to. These include:
- Warning lights: If a warning light on your car’s dashboard comes on, this could be a sign that your transmission fluid temperature is too hot.
- Burning smell: If there is a sweet burning smell in your car, it could point to your transmission fluid needing to be refilled or changed.
- Difficulty changing gears: As mentioned earlier, if it doesn’t feel smooth to change your car’s gears, this could point to a problem with your transmission fluid or something else that’s wrong in the car’s transmission system.
- Brown transmission fluid: Your car’s transmission fluid should be red in color and be clear. If it’s become brown, this means something’s wrong.
- Leaks: If you notice puddles underneath your car, especially if the liquid is red in color, then you know the transmission fluid is leaking out of your car.
How do I find my transmission code?
If you need to find out what kind of transmission you have, you will need to know your transmission code. While this might sound complex, it’s something you can easily find yourself.
What you need to do is check the inside of your driver’s side door in your car. Here, there’s a white card that’s been stuck to the inside of your door and it will have various details about your vehicle, such as the year in which it was made, its engine specifications, and its transmission.
You’ll see the letters “TR” which stand for transmission and a code. Another way in which you can find out your transmission number is to check the owner’s manual or take a peek underneath the hood of your car.
Many cars will have stickers here to inform you of important information, as well as transmission data. For example, most cars on the road will have a 4, 6, or HEMI transmission, as these are standard sizes.
Finally, you might wonder if your car’s VIN number will tell you what your transmission code is. The VIN number is essentially a number that has 17 digits in it. It holds a wealth of information, such as the engine your car has, and more.
However, it won’t give you much information related to the type of transmission you have or what number it is, so you’re better off using the previously-mentioned methods for finding out that information about your car.
On the topic of transmission codes, you might be wondering how to find a transmission error code with a car scanning device.
For starters, if your “check engine” light comes on and you don’t think that it’s something else in your car that could be causing it, the problem could be with your car’s transmission.
There are some common codes that signal problems with your transmission, which will show up on your scanning device. These include:
- P0218: This code usually points to a problem with your transmission fluid if it appears on its own without the presence of other codes, and it’s very common. If it is displayed on your scanner along with other trouble codes, this can be a more complicated problem that requires you to take your car to the mechanic.
- P0700: This signals a transmission system malfunction. Symptoms include poor mileage, engine stalling, and difficulty with shifting gears.
- P0715: This signals a problem with the input/turbine speed sensor.
- P0702: This error code refers to output speed sensor circuit malfunctions. The output speed sensor is a component that controls your speedometer.
The above are some common transmission error codes that you will gain with the use of a car-scanning device.
Conclusion
Your car’s transmission is crucial to look after and maintain, which is why it’s worth purchasing your own transmission code reader.
In this article, we’ve looked at the best transmission code reader along with four alternatives so you can maintain the health of your car’s transmission and enjoy many more miles of driving your car.
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