A basic code reader tells you a fault exists. A bi directional scan tool goes further: it sends commands back to the vehicle so you can cycle injectors, run cooling fans, actuate EVAP solenoids, retract electronic parking brakes, and watch which components respond. That two-way active-test ability turns diagnosis from guesswork into a process of elimination, and it is the single biggest difference between a $30 code reader and a real diagnostic tool.
1
Quick Verdict
The TOPDON TopScan Lite is a phone-connected OBD2 scan tool with full-system diagnostics, bidirectional controls, eight service resets, AI repair assistance, and CAN-FD support. Core diagnostics are free for life, while advanced features are included for the first year and require a subscription afterward.
Pros & Cons
Pros
- Offers bidirectional testing to help identify components that do not respond.
- Combines full-system diagnostics with service resets and repair information.
- Includes free-for-life access to core diagnostics.
- Supports CAN-FD and multiple gateway-unlock functions.
Cons
- Advanced features require a monthly, quarterly, or yearly subscription after the first year.
- FCA, Renault, and Nissan gateway-unlock access requires the user's own account.
Product Details
Specifications
| Color | Black |
|---|---|
| Size | 1 |
| Dimensions | 3.31 x 1.98 x 1.07 Inches |
| Weight | 0.06172943336 Pounds |
| Product Group | Automotive Parts and Accessories |
| Binding | Automotive |
Best For / Avoid If
Best for buyers prioritizing
- Offers bidirectional testing to help identify components that do not respond.
- Combines full-system diagnostics with service resets and repair information.
- Includes free-for-life access to core diagnostics.
Consider another option if
- Advanced features require a monthly, quarterly, or yearly subscription after the first year.
- FCA, Renault, and Nissan gateway-unlock access requires the user's own account.
2
Quick Verdict
The XTOOL A30M V2.0 is a Bluetooth 4.0 OBD2 scanner with full-system diagnostics, bidirectional controls, 26 reset and relearn functions, CAN FD support, and FCA AutoAuth access for compatible vehicles. Software updates are provided for the app's service functions without a subscription fee, while compatibility and available functions vary by vehicle.
Pros & Cons
Pros
- Combines full-system scanning with bidirectional controls and multiple service functions.
- Supports newer vehicle protocols through CAN FD and FCA AutoAuth compatibility.
- Includes lifetime free software updates for app service functions.
- Provides multilingual support for 22 languages, with English set by default.
Cons
- FCA AutoAuth access requires a separate account and payment through the official FCA AutoAuth website.
- Service functions and vehicle coverage vary by model, so compatibility should be checked before purchase.
Product Details
Specifications
| Color | Black |
|---|---|
| Product Group | Automotive Parts and Accessories |
| Binding | Automotive |
Best For / Avoid If
Best for buyers prioritizing
- Combines full-system scanning with bidirectional controls and multiple service functions.
- Supports newer vehicle protocols through CAN FD and FCA AutoAuth compatibility.
- Includes lifetime free software updates for app service functions.
Consider another option if
- FCA AutoAuth access requires a separate account and payment through the official FCA AutoAuth website.
- Service functions and vehicle coverage vary by model, so compatibility should be checked before purchase.
3
Quick Verdict
The Innova 5610 is a bidirectional OBD2 scan tool with enhanced data access for select ABS, SRS, transmission, and engine systems. It supports select OBD2 vehicles from 1996 through 2023, includes free updates, and offers ASE-certified support.
Pros & Cons
Pros
- Offers bidirectional controls in addition to standard diagnostic functions.
- Provides access to enhanced live data for several vehicle systems.
- Includes free updates without subscription fees.
- Has phone and email support from an American support team.
Cons
- Compatibility and available functions vary by vehicle, so Innova's coverage checker is required.
- The tool is not universal across all makes and models.
Product Details
Specifications
| Size | 1 Count(Pack of 1) |
|---|---|
| Dimensions | 7 x 3.75 x 1 inches |
| Product Group | Automotive Parts and Accessories |
| Binding | Automotive |
Best For / Avoid If
Best for buyers prioritizing
- Offers bidirectional controls in addition to standard diagnostic functions.
- Provides access to enhanced live data for several vehicle systems.
- Includes free updates without subscription fees.
Consider another option if
- Compatibility and available functions vary by vehicle, so Innova's coverage checker is required.
- The tool is not universal across all makes and models.
4
Quick Verdict
The TOPDON AD900 Lite is a full-system OBD2 scan tool with bidirectional controls, wireless Bluetooth 5.0 diagnosis, an 8-inch touchscreen, and eight listed reset-service categories. It includes a 10,000mAh battery, one-year warranty, and two years of free software updates.
Pros & Cons
Pros
- Provides bidirectional testing in addition to code reading and clearing.
- Offers wireless and cabled connectivity options through the Bluetooth VCI and VCI cables.
- Includes a large 8-inch display, Android 11.0, and a stated 12-hour operating time.
- Includes a one-year warranty and two years of free software updates.
Cons
- Battery testing is listed as optional rather than included as a standard feature.
- The DTC repair guide compatibility specified in the listing is limited to Chrysler, Dodge, Jeep, and Fiat vehicles from 2010 to 2014.
Product Details
Best For / Avoid If
Best for buyers prioritizing
- Provides bidirectional testing in addition to code reading and clearing.
- Offers wireless and cabled connectivity options through the Bluetooth VCI and VCI cables.
- Includes a large 8-inch display, Android 11.0, and a stated 12-hour operating time.
Consider another option if
- Battery testing is listed as optional rather than included as a standard feature.
- The DTC repair guide compatibility specified in the listing is limited to Chrysler, Dodge, Jeep, and Fiat vehicles from 2010 to 2014.
5
Quick Verdict
The GEARWRENCH GWSMARTBT is a bi-directional diagnostic scan tool designed to provide OE-level diagnostics through a smart device. Listed features include live actuation tests, 23 reset and relearn functions, live data mapping, and freeze-frame capture.
Pros & Cons
Pros
- Bi-directional control supports live actuation tests
- Includes 23 listed reset and relearn functions
- Free software updates are listed without subscriptions or fees
Product Details
Specifications
| Dimensions | 3.4 x 2.1 x 0.9 inches |
|---|---|
| Weight | 0.2425084882 pounds |
| Product Group | Automotive Parts and Accessories |
| Binding | Automotive |
Best For / Avoid If
Best for buyers prioritizing
- Bi-directional control supports live actuation tests
- Includes 23 listed reset and relearn functions
- Free software updates are listed without subscriptions or fees
6
Quick Verdict
The THINKCAR THINKSCAN 689BT is a bidirectional automotive diagnostic scanner with all-system diagnostics, ECU coding, 34 services, wireless updates, CAN FD, and DoIP support. FCA AutoAuth functions require an FCA account and paid membership, and coding and service compatibility vary by vehicle model and year.
Pros & Cons
Pros
- Combines bidirectional controls, all-system diagnostics, ECU coding, and service functions in one scan tool.
- Supports CAN FD and DoIP protocols for compatible vehicles.
- Includes wireless updates without subscription fees.
- Lists support for 140 worldwide vehicle makes, including passenger cars, 12V pickups, hybrids, and SUVs.
Cons
- FCA AutoAuth use requires registration for an FCA account and payment of a membership fee.
- ECU coding and service functions vary by vehicle model and year, so compatibility must be checked before purchase.
Product Details
Specifications
| Color | Black |
|---|---|
| Dimensions | 7.87401574 x 4.724409444 x 1.3779527545 inches |
| Weight | 1.873929227 pounds |
| Product Group | Automotive Parts and Accessories |
Best For / Avoid If
Best for buyers prioritizing
- Combines bidirectional controls, all-system diagnostics, ECU coding, and service functions in one scan tool.
- Supports CAN FD and DoIP protocols for compatible vehicles.
- Includes wireless updates without subscription fees.
Consider another option if
- FCA AutoAuth use requires registration for an FCA account and payment of a membership fee.
- ECU coding and service functions vary by vehicle model and year, so compatibility must be checked before purchase.
7
Quick Verdict
The XTOOL A30D is a wireless, bidirectional OBD2 scanner with all-system diagnostics, 19 maintenance reset functions, live data, and support for CAN-FD and FCA AutoAuth. Vehicle coverage and special functions vary by make and year, so compatibility should be confirmed before purchase.
Pros & Cons
Pros
- Combines bidirectional testing with all-system diagnostics.
- Includes 19 maintenance reset and relearn functions without additional charges.
- Supports CAN-FD and FCA AutoAuth on applicable vehicles.
- Offers wireless operation and live-data display with up to 8 PIDs.
Cons
- Vehicle coverage and available functions vary by make and year and should be confirmed before purchase.
- FCA AutoAuth requires a personal AutoAuth account and active subscription, which are not included.
- The listed iOS and Android requirements may limit compatibility with older devices.
Product Details
Specifications
| Color | Black |
|---|---|
| Size | A30D |
| Dimensions | 3.94 x 5.51 x 1.97 Inches |
| Product Group | Automotive Parts and Accessories |
| Binding | Automotive |
Best For / Avoid If
Best for buyers prioritizing
- Combines bidirectional testing with all-system diagnostics.
- Includes 19 maintenance reset and relearn functions without additional charges.
- Supports CAN-FD and FCA AutoAuth on applicable vehicles.
Consider another option if
- Vehicle coverage and available functions vary by make and year and should be confirmed before purchase.
- FCA AutoAuth requires a personal AutoAuth account and active subscription, which are not included.
- The listed iOS and Android requirements may limit compatibility with older devices.
8
Quick Verdict
The THINKCAR THINKSCAN 662 is an OBD2 diagnostic scanner with bidirectional active tests, ECM, TCM, ABS and SRS scanning, 12 reset functions, CAN FD support and integrated AutoAuth for applicable FCA SGW vehicles. It includes a 6.2-inch touchscreen, physical buttons, Wi-Fi updates and lifetime free software updates.
Pros & Cons
Pros
- Bidirectional control and active-test functionality is included.
- Supports multiple service resets and system-level diagnostics.
- CAN FD support and integrated AutoAuth expand compatibility for applicable vehicles.
- Includes automatic VIN recognition, data visualization and saved diagnostic reports.
- Lifetime free software updates are provided through Wi-Fi.
Cons
- FCA AutoAuth access is not included; users must register and pay separately through the official FCA AutoAuth website when required.
- Vehicle-specific compatibility should be confirmed before purchase.
Product Details
Specifications
| Product Group | Automotive Parts and Accessories |
|---|
Best For / Avoid If
Best for buyers prioritizing
- Bidirectional control and active-test functionality is included.
- Supports multiple service resets and system-level diagnostics.
- CAN FD support and integrated AutoAuth expand compatibility for applicable vehicles.
Consider another option if
- FCA AutoAuth access is not included; users must register and pay separately through the official FCA AutoAuth website when required.
- Vehicle-specific compatibility should be confirmed before purchase.
Before you buy, it is worth reading Automotive Multimeter Buying Guide, OBD2 Scanner Buying Guide for Beginners and Best Bluetooth Scan Tool.
Quick Verdict
- Best budget entry: TOPDON TopScan Lite OBD2 Scanner, the cheapest route into active tests, but advanced features move to a subscription after year one.
- Best no-subscription value: XTOOL A30D, lifetime free updates, 19 resets, and CAN-FD plus FCA support in a phone app.
- Best all-round phone scanner: XTOOL A30M V2.0, 26 resets and 8-stream live graphing with no subscription.
- Best budget standalone: THINKCAR THINKSCAN 662, a 6.2-inch touchscreen tablet with lifetime updates.
- Best handheld with US support: Innova 5610, no fees and ASE-certified phone support, but verify coverage for your vehicle.
- Best mid-range tablet: TOPDON AD900 Lite, an 8-inch screen and Bluetooth 5.0 VCI, with only 8 resets.
- Best for repair shops: THINKCAR THINKSCAN 689BT, ECU coding, 34 services, and DoIP, priced accordingly.
- Brand-name alternative: GEARWRENCH GWSMARTBT, no-fee phone-based control with thinner documented compatibility.
How We Chose
We evaluated each tool on manufacturer-listed specifications: bidirectional capability, reset and service counts, software update and subscription terms, protocol support (CAN-FD, DoIP, FCA AutoAuth), hardware, and warranty or support options. Published ratings were not a usable signal for this guide because none of these listings carried a meaningful review count at the time of writing. Compatibility is the biggest failure point with bidirectional tools, so where a manufacturer asks buyers to confirm fitment by VIN, we treat that step as essential rather than optional.
Bi Directional Scan Tool Comparison
| Model | Runs on | Resets / services | Software updates | CAN-FD | FCA AutoAuth |
|---|---|---|---|---|---|
| TOPDON TopScan Lite | Smartphone app | 8 resets | Free first year, then subscription for advanced features | Listed | Gateway unlock, own account |
| XTOOL A30D | Smartphone app (Android 9+/iOS 10+) | 19 resets | Lifetime free | Listed | Listed, own account |
| GEARWRENCH GWSMARTBT | Smart device | 23 reset/relearn functions | Free, no fees | – | – |
| XTOOL A30M V2.0 | Smartphone or tablet app (BT 4.0) | 26 resets | Lifetime free | Listed (GM 2020+) | Listed, 2018+, own account |
| THINKCAR THINKSCAN 662 | Standalone 6.2-inch touchscreen | 12 resets | Lifetime free | Listed | Listed, 2018+, own account |
| TOPDON AD900 Lite | Standalone 8-inch touchscreen (BT 5.0 VCI) | 8 resets | 2 years free | – | – |
| Innova 5610 | Standalone handheld | – | Free, no subscription | – | – |
| THINKCAR THINKSCAN 689BT | Standalone Android 10 tablet | 34 services | Free, no subscription | Listed | Portal included, own paid account |
Not provided means the manufacturer listing does not specify that field. Prices are observations at the time of writing and can change.
Compatibility and Buying Advice
- Vehicle age: every tool here targets 1996 and newer OBD2 vehicles. Innova’s listing is more specific: 1996–2023, with 2024 described as coming soon.
- FCA security gateway: 2018+ Chrysler, Jeep, Dodge, and Fiat vehicles require FCA AutoAuth. On the XTOOL A30M and A30D, THINKCAR 662 and 689BT, and TOPDON TopScan Lite, registration and membership are paid by you, separately from the tool.
- CAN-FD: newer vehicles, including 2020+ GM models, use this protocol. The A30M, A30D, 662, 689BT, and TopScan Lite list CAN-FD support; the Innova 5610, AD900 Lite, and GEARWRENCH listings do not specify it.
- DoIP: only the THINKSCAN 689BT lists this faster protocol, which matters mainly for late-model European vehicles.
- VIN checks: active tests and resets vary by make, model, and year. XTOOL and THINKCAR both ask you to confirm compatibility by VIN before purchase, do it, and get the answer in writing.
How to Choose a Bi Directional Scan Tool
- Confirm bidirectional coverage for your exact vehicle. Marketing coverage percentages are not a guarantee for your VIN.
- Model the total cost. A $51.99 tool that needs a subscription after year one can cost more over three years than a $99.99 tool with lifetime free updates.
- Match the form factor to your workflow. Phone-based tools (TopScan Lite, GEARWRENCH, A30D, A30M) are cheapest and most portable; standalone tablets (662, AD900 Lite, 689BT) boot independently and suit a shop environment; the 5610 fits buyers who want a dedicated handheld.
- Count the resets you will actually use. Oil, EPB, SAS, ABS bleeding, BMS, throttle relearn, and injector coding cover most home maintenance. Paying for 34 services only makes sense if you wrench on many vehicles.
- Decide if coding matters. Only the 689BT lists ECU coding, and coding functions vary by model and year.
- Check warranty and support. The A30D lists a 2-year repair warranty, the AD900 Lite a 1-year warranty and 2 years of updates, and Innova offers US-based ASE-certified phone support.
FAQ
What does a bi directional scan tool actually do?
It communicates both ways with the ECU. Besides reading and clearing codes, it sends commands to components, running a fuel pump, cycling injectors, spinning cooling fans, or retracting an electronic parking brake, so you can confirm whether a part responds without disassembling anything.
Do I need bidirectional control, or is a code reader enough?
A code reader is enough to read and clear a check-engine light. Bidirectional control earns its cost when you troubleshoot intermittent electrical faults, service brakes with electric parking brakes, or perform resets and relearns after repairs.
Will one of these work on my car?
Most 1996 and newer vehicles with an OBD2 port are covered for basic diagnostics, but active tests and resets vary by vehicle. Two modern complications matter: 2018+ FCA models need a paid AutoAuth account, and some 2020+ GM vehicles need CAN-FD support. Verify by VIN before buying.
Do any of these require subscriptions?
The XTOOL A30M and A30D, THINKCAR 662 and 689BT, GEARWRENCH GWSMARTBT, and Innova 5610 all list free updates with no subscription fees. The TOPDON TopScan Lite is free for the first year, then charges for advanced features, while the AD900 Lite includes two years of free updates. FCA AutoAuth is always a separate paid account regardless of tool.
What is the cheapest bi directional scan tool?
The TOPDON TopScan Lite at an observed $51.99, provided you accept its first-year-then-subscription structure for advanced features such as active tests.
Final Verdict
For most home mechanics, the XTOOL A30M V2.0 is the most complete package in this comparison: 26 resets, 8-stream graphing, CAN-FD and FCA support, and lifetime free updates at a mid-tier price. If budget rules, the A30D delivers the same no-fee model for less, while the TopScan Lite is the lowest-cost entry if a subscription after year one does not bother you. Choose the THINKSCAN 662 for an affordable standalone screen, the Innova 5610 for handheld simplicity and US-based support after a coverage check, and the THINKSCAN 689BT if you run a shop and need coding depth and DoIP. Whichever you pick, verify your VIN’s coverage first, that single step prevents most returns.
