Unlocking your car’s secrets is easier than you think with the Best Car Diagnostic Tester. These clever devices plug into your vehicle’s onboard computer, giving you a direct line to the information it holds. Whether you’re facing a mysterious dashboard light or suspect an underlying issue, a car diagnostic tester, also known as an OBD-II scanner, can be your first step in understanding what’s happening under the hood. Instead of immediately heading to a mechanic, these tools empower you to diagnose problems yourself, potentially saving time and money.
Navigating the world of car diagnostic testers can be daunting, especially for beginners. The market offers a wide range of options, each with different features and capabilities. Having tested numerous OBD-II scanners over the years, we’ve gained valuable insights into which ones truly stand out. We’ve compiled a list of the best car diagnostic testers available, ensuring you find the right tool for your needs. Keep reading to learn more about how these testers work and what those cryptic error codes actually mean.
Among our top recommendations, the Topdon TopScan shines as a wireless and remarkably effective option for pinpointing car troubles. For budget-conscious users, the Launch CR529, priced around $40, offers excellent value. If you’re seeking a more professional-grade experience, the Topdon Phoenix Lite 2 delivers advanced diagnostic features, though it comes with a higher price tag of $799.
Here’s a quick rundown of the best car diagnostic testers you can purchase today.
Tom Pritchard
Tom is the UK Phones Editor at Tom’s Guide, with expertise in mobile technology and a passion for electric vehicles. He brings extensive knowledge to car tech reviews.
Quick List: Top Car Diagnostic Testers
Based on our hands-on evaluations, here are the top car diagnostic testers currently available. Scroll down for detailed reviews of each product and discover why they earned their place on our list.
Topdon TopScan wireless car diagnostic toolTopdon TopScan: Best mobile car diagnostic tester
- Topdon TopScan
This Bluetooth car diagnostic tester is incredibly user-friendly and packed with professional-grade features in a compact design. Expect comprehensive diagnostics, repair guidance, parts information, and even predictive analysis to foresee potential problems.
Explore the Topdon TopScan in detail
Launch CR529 handheld OBD-II scanner on a white backdropLaunch CR529: Best budget-friendly car diagnostic tester- Launch CR529
Don’t let its size fool you; the Launch CR529 is a powerful car diagnostic tool offering all essential OBD-II scanner functions, plus some advanced features typically found in more expensive models. Benefit from lifetime support and software updates, making it an exceptional value.
Discover more about the Launch CR529
Topdon Phoenix Lite 2 professional car scanner and tabletTopdon Phoenix Lite 2: Best durable car diagnostic tester for professionals and DIYers- Topdon Phoenix Lite 2
Resembling a rugged tablet, the Topdon Phoenix Lite 2 is built for both professionals and serious DIY enthusiasts. Beyond its robust build, it delivers powerful diagnostic capabilities, making it an ideal choice for those needing a scanner that can withstand demanding environments.
Learn more about the Topdon Phoenix Lite 2
Ancel BD310 dual-purpose car diagnostic scannerAncel BD310: Best versatile car diagnostic tester
- Ancel BD310
The Ancel BD310 is not just a capable car diagnostic tester; it can also enhance your car’s dashboard by displaying real-time engine specifications. Combine this with its user-friendly design, smartphone compatibility, and affordable price, and you have a versatile tool.
Read more about the Ancel BD310
Carly OBD scanner and companion app interfaceCarly OBD-II Scanner: Best car diagnostic tester with companion app- Carly OBD-II Scanner
The Carly scanner’s value is highly dependent on your car make, with brands like VW, BMW, and Ford benefiting the most from its features. However, it boasts one of the most comprehensive and user-friendly companion apps available, offering extensive customization and professional-level diagnostic tests.
Explore the Carly OBD-II Scanner in detail
What Makes These the Best Car Diagnostic Testers?
Why Trust Tom’s Guide? Our team of expert reviewers dedicates countless hours to rigorously testing and evaluating products to bring you unbiased and reliable recommendations. Learn more about our testing methodology.
Best Mobile Car Diagnostic Tester
(Image credit: Topdon)
1. Topdon TopScan
Ideal for Deep Car System Analysis
Read our expert review
Specifications:
- Display/Size: None
- Bluetooth/Handheld: Yes/No
- I/M Readiness Test: Yes
- Live Data Display: Yes
- Number of Keys: None
- Warranty: 2 years
- Size: 3.2 x 2.0 x 1.1 inches
- Weight: 2.6 ounces
Reasons to Buy:
- Excellent automotive diagnostic coverage
- Real-time live data monitoring
- Unique performance indicators
- Comprehensive maintenance item coverage
Reasons to Avoid:
- Larger, heavier transmitter
- Subscription required for some features after one year
The Topdon TopScan might appear unassuming, but this compact car diagnostic tester packs a powerful punch. It’s far more than just a standard Bluetooth OBD-II module that streams data to your smartphone app. I was particularly impressed by its advanced capabilities that exceed those of many competitors in its class.
Beyond basic fault detection and I/M Readiness tests, the TopScan goes further by assessing vehicle performance and efficiency. It can even estimate your car’s horsepower and torque figures. Remarkably, it offers features often absent in car diagnostic testers costing ten times as much. Whether you aim to fine-tune your vehicle’s performance or simply ensure its roadworthiness, the TopScan is an invaluable tool to have in your garage.
Read our comprehensive Topdon TopScan review
Best Budget Car Diagnostic Tester
(Image credit: Future)
2. Launch CR529
Top-Tier OBD-II Scanning for Under $50
Read our expert review
Specifications:
- Display/Size: Color/ 2.8-inches
- Bluetooth/Handheld: No/Yes
- I/M Readiness Test: Yes
- Live Data Display: Yes
- Number of Keys: 8
- Warranty: 1 year
- Size: 6.5 x 3.8 x 1.2 inches
- Weight: 11 ounces
Reasons to Buy:
- Very affordable
- Lifetime software updates
- Convenient pre-inspection report feature
Reasons to Avoid:
- Lacks manufacturer-specific codes
- Feels somewhat heavy
- Limited 1-year warranty
In my opinion, the Launch CR529 delivers unmatched value as a car diagnostic tester. Its attractive price of around $38 is just the beginning; the diagnostic capabilities it offers at this price point are truly impressive. I was genuinely surprised by the level of functionality packed into such a budget-friendly device.
Of course, some compromises are expected with a scanner this affordable. It doesn’t support manufacturer-specific codes and has a slightly hefty feel. However, it still provides live data, an instant inspection feature, and remarkably detailed insights into your vehicle’s systems. The inclusion of lifetime updates ensures this scanner remains useful for years to come, without any subscription fees.
While the CR529 might not cater to professional mechanics demanding advanced features, it’s an excellent choice for most car owners seeking a reliable and affordable car diagnostic tester.
Read our full Launch CR529 review
Best Professional-Grade Car Diagnostic Tester
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(Image credit: Future)](https://target.georiot.com/Proxy.ashx?tsid=45724&GR_URL=https%3A%2F%2Famazon.com%2Fdp%2FB085TG89H4%3Ftag%3Dhawk-future-20%26ascsubtag%3Dtomsguide-us-1224700782076728613-20)
3. Topdon Phoenix Lite 2
Bridging the Gap Between DIY and Professional Diagnostics
Read our expert review
Specifications:
- Display/Size: Color/8-inch
- Bluetooth/Handheld: Yes/Yes
- I/M Readiness Test: Yes
- Live Data Display: Yes
- Number of Keys: Touchscreen
- Warranty: 2 years
- Size: 10.2 x 7.2 x 1.7 inches
- Weight: 2.6 pounds
Reasons to Buy:
- Professional-level OBD scanning capabilities
- Versatile handheld with Wi-Fi and Bluetooth connectivity
- Large 8-inch touchscreen display
- Extensive suite of diagnostic tests and live data features
- Includes adapters and a protective hard case
Reasons to Avoid:
- Bulky and heavy design, can be cumbersome
- Higher price point
- Subscription required after two years for updates
The Topdon Phoenix Lite 2 car diagnostic tester is a significant investment, costing more than many other capable OBD-II scanners, but it justifies its price with a wealth of features. It’s ideally suited for both amateur car enthusiasts and professional mechanics.
A standout feature of the Phoenix Lite 2 is its completely wireless operation. The control pad connects via Bluetooth to a receiver plugged into your car’s OBD port, allowing for exceptional freedom of movement around the vehicle. While the scanner itself is substantial and heavy, it includes a kickstand and rugged construction designed to withstand workshop conditions.
It also offers live data graphing, detailed fault code information, and numerous advanced features that are beyond the reach of most budget scanners. Keep in mind that firmware updates are included for two years, after which an annual subscription of $495 is required.
Read our in-depth Topdon Phoenix 2 Lite review
Best Dual-Purpose Car Diagnostic Tester
Ancel BD310 OBD-II scanner displaying car diagnostics
Ancel BD310 (Image credit: Tom’s Guide)
4. Ancel BD310
A Versatile OBD-II Scanner That Does Double Duty
Read our expert review
Specifications:
- Display/Size: Color/2 inches
- Bluetooth/Handheld: Yes/Yes
- I/M Readiness Test: Yes
- Live Data Display: Yes
- Number of Keys: 4
- Warranty: 3 years
- Size: 5.1 x 2.4 x 0.6 inches
- Weight: 5.4 ounces
Reasons to Buy:
- Lightweight and compact design
- Functions as both a scanner and a secondary car display
- Offers handheld and Bluetooth scanning options
Reasons to Avoid:
- Minimalist interface
- Small screen size
The Ancel BD310 is a dual-purpose car diagnostic tester, functioning as a traditional handheld scanner and, when connected to a smartphone via Bluetooth, as a secondary display for your car’s vital engine stats.
We found the BD310 exceptionally convenient to keep on hand due to its small and light form factor, easily fitting in a glovebox. While the 2-inch screen is compact and the four-button interface felt a bit awkward, it didn’t hinder the process of diagnosing car issues.
The 56-inch cable offers ample reach when working under the hood, and the BD310 is capable of performing essential tasks like I/M inspection readiness tests and providing performance data, including coolant temperature, engine timing, and RPM.
Read our complete Ancel BD310 review.
Best Car Diagnostic Tester with Companion App
Carly OBD 2 scanner showcasing its design
(Image credit: Carly)
5. Carly OBD-II Scanner
A Capable Scanner, Best Suited for Specific Car Brands
Read our expert review
Specifications:
- Display/Size: No
- Bluetooth/Handheld: Yes/No
- I/M Readiness Test: No
- Live Data Display: Yes
- Number of Keys: None
- Warranty: Lifetime
- Size: 2.9 x 1.5 x 0.7 inches
- Weight: 0.7 ounces
Reasons to Buy:
- User-friendly interface
- Customization options
- Live data display
- Coverage for maintenance and repairs
- Lifetime warranty and updates
Reasons to Avoid:
- Feature availability varies by car model
- App subscriptions can become costly
The Carly OBD Scanner provides a rich set of features for its price, and we were particularly impressed by the quality of its companion app. While many Bluetooth scanners offer basic app functionality, Carly stands out with one of the best apps we’ve tested.
Beyond just reading codes and diagnosing problems, the app offers repair assistance to help you get your car running again and tools to assess used cars for potential issues. The lifetime warranty is a significant bonus, offering long-term peace of mind.
However, the breadth of features available depends on your specific car model. Compatibility should be verified before purchasing, as full functionality is not guaranteed across all makes and models. Additionally, accessing advanced features beyond basic OBD functions requires an ongoing app subscription, which can add up over time.
Read our detailed Carly OBD scanner review
Other Car Diagnostic Testers We’ve Tested
Innova CarScan Mobile 1000 Review Innova CarScan Mobile 1000 (★★★★☆)
This innovative Bluetooth car diagnostic tester inherits Innova’s impressive features, including predictive diagnostics, in a completely wireless, phone-based format. Its exceptionally simple setup process makes it a standout Bluetooth-only option.
Read the full Innova CarScan Mobile 1000 review
ThinkCar ThinkDiag TKD01 Bluetooth car diagnostic adapter
ThinkCar ThinkDiag TKD01 (★★★★☆)
While larger than typical Bluetooth OBD-II adapters, the TKD01’s robust build makes it virtually indestructible. It offers a wide range of manufacturer-specific error codes and advanced fault-code analysis that can resolve minor issues without mechanic intervention. Note that a $40 subscription is required after the first year.
Read our full ThinkCar ThinkDiag TKD01 review.
Autel AutoLink AL539 (★★★☆☆)
This car diagnostic tester excels at diagnosing electrical problems, thanks to its integrated multimeter. It can identify issues like damaged cables, shorts, and blown fuses. It also provides extensive live data and pre-inspection readiness checks.
Read our full Autel AutoLink AL539 review
Frequently Asked Questions About Car Diagnostic Testers
What is a Car Diagnostic Tester (OBD-II Scanner)?
Ever wondered how mechanics pinpoint car problems? They don’t dismantle engines piece by piece. Instead, they use a car diagnostic tester, also known as an OBD-II scanner, which plugs into your car’s OBD port to access data from the onboard computer.
At their most basic, these testers read and interpret error codes flagged by your car when it detects an issue. More advanced models offer real-time monitoring of vehicle systems and can even predict potential future problems.
What is the OBD-II Port?
The On-Board Diagnostics Version Two (OBD-II) port is a standardized port found in nearly all passenger vehicles sold in the US since 1996, Canada since 1998, the EU since 2004, and Australia, Mexico, and New Zealand since 2006.
This port serves as the interface to your car’s computer. Various devices can connect to it, including car diagnostic testers, insurance telematics devices, and modern dashcams.
If you’re unsure of your OBD-II port’s location, here’s a guide on finding your car’s OBD-II port in North American vehicles. For locations worldwide, refer to this guide on finding your OBD-II/EOBD port globally.
What is a DTC?
DTC stands for Diagnostic Trouble Code, the error code generated by a car’s OBD system when it detects a problem. These codes are read by car diagnostic testers, enabling users to understand the nature of the issue. Many DTCs are standardized across vehicle makes and models, though some manufacturers use proprietary DTCs specific to their vehicles.
Understanding DTC Meanings
DTCs, if unfamiliar, can seem like random letter and number combinations. However, they follow a logical structure that reveals the type of error detected.
The first letter indicates the affected vehicle system: Powertrain (P), Body (B), Chassis (C), or Network (N). The second character, a number, denotes whether the code is generic (0) or manufacturer-specific (1).
The third character specifies the subsystem involved:
- 1: Fuel and air metering
- 2: Injector circuit (fuel and air metering)
- 3: Ignition system or misfire
- 4: Auxiliary emissions
- 5: Vehicle speed controls and idle control systems
- 6: Computer auxiliary outputs
- 7, 8, 9: Transmission and gearbox faults
- A, B, C: Hybrid-specific propulsion faults
The fourth and fifth characters pinpoint the exact fault, ranging from 0 to 99.
Car diagnostic testers decode these error codes into understandable descriptions. More advanced models provide even richer information. While online resources like Google can be helpful, the sheer number of possible DTCs (over 5,000) can be overwhelming.
Not all DTCs signal critical problems. While they identify serious issues, some codes may simply indicate a minor anomaly, like a slightly elevated engine temperature.
How to Choose the Best Car Diagnostic Tester for Your Needs
For insight into your vehicle’s health and potential issues, a car diagnostic tester is invaluable. It’s the same technology used by dealerships and repair shops. Why not have this capability at your fingertips? However, not all car diagnostic testers are created equal. There are two main types:
Handheld Car Diagnostic Testers: These come with an integrated screen and a cable to connect to your car’s OBD port. Wireless Car Diagnostic Testers: These plug into the OBD port and connect wirelessly via Bluetooth to a smartphone or tablet for displaying data.
Regardless of the type, numerous high-performing car diagnostic testers are available for under $200, and some for even under $30. Key factors to consider when choosing the best car diagnostic tester include size, weight, and the ability to accurately read fault codes and live data. Essential criteria include:
- Easy Setup: A quick and straightforward setup is crucial for prompt diagnostics.
- Fault Codes and Explanations: The best testers not only identify fault codes but also provide clear explanations, aiding in DIY repairs or informed communication with mechanics.
- I/M Readiness Check: A valuable feature for verifying emissions system readiness for state inspections.
- Accuracy: Reliable and accurate results are paramount for effective diagnostics.
- Size and Weight: A compact and lightweight tester is more likely to be kept in the car for on-the-go diagnostics.
- Live Data: Real-time monitoring of engine parameters can be essential for tracking down intermittent issues.
- Graphs: Visual data representation through graphs enhances data interpretation, especially for comparative analysis.
- Warranty: Opt for testers with extended or lifetime warranties for long-term reliability.
Choosing the right car diagnostic tester depends on your preferences – whether you prefer the convenience of a smartphone-connected wireless device or a standalone handheld unit.
Consider longevity by selecting a tester with lifetime warranty or software updates to ensure it remains compatible with evolving automotive technology.
For handheld testers, prioritize screen size and clarity, aiming for a large, bright, icon-driven display for ease of use. If durability is a concern, ruggedized models with shock-absorbing bumpers are recommended.
Look for added features such as electrical multimeters, manufacturer-specific code reading, or PDF report export capabilities.
The affordability of these sophisticated devices is remarkable, with professional-grade features available for under $100 – less than the cost of an hour of mechanic labor, making it a worthwhile investment.
How We Test Car Diagnostic Testers
To evaluate car diagnostic testers, I used my 2014 Audi A4 Allroad over several weeks, both in the garage and on the road. Each tester was connected to the car’s OBD-II port, and VIN reporting accuracy was verified.
For wireless testers, connections were established with an Apple iPad Pro, Microsoft Surface, or Samsung Galaxy S9+ via Bluetooth or Wi-Fi. Handheld testers were powered directly through the OBD-II port connection.
Cord lengths (for handhelds) and wireless ranges were measured. With the engine running, engine and vital systems were monitored. Subsequently, the engine oil temperature sensor was intentionally disconnected to induce a fault.
The fault code details provided by each tester were assessed. The issue was then resolved, the check engine light cleared, and the error code erased using the tester.
On-road testing involved observing real-time operating data display, such as engine speed, timing, and coolant temperature, noting whether data was presented numerically, graphically, or via gauges.
Understanding fault codes is crucial. All codes consist of four numbers and a letter prefix:
- Powertrain (P)
- Body (B)
- Chassis (C)
- Undefined (U)
Of the approximately 5,000 possible diagnostic fault codes, generic codes (starting with 0 numerically) are universal across vehicles, covering common issues like air temperature and throttle position. Manufacturer-specific codes (starting with 1) are unique to particular carmakers, indicating specialized hardware or deeper issue analysis.
For example, a P0098 code typically indicates a problem with the engine’s intake air temperature sensor. In contrast, a Ford-specific P1112 code signifies that the intake air temperature sensor is reporting intermittent values and likely needs replacement.
