The Innova 3120 series of handheld scanners has become a familiar tool for both seasoned mechanics and DIY car enthusiasts. Among them, the Innova Obd2 3120d scanner aims to offer a balance of features and affordability for diagnosing vehicle issues. But does this scanner truly live up to its promises, especially when tackling the complexities of older OBD1 systems alongside modern OBD2? We decided to put the Innova 3120D to the test, focusing particularly on its performance with older vehicles, specifically the 94 and 95 F-body cars, to see if it’s the right diagnostic tool for your needs.
First Impressions: Unboxing and Initial Setup
The Innova OBD2 3120D arrives in practical, zippered cases – one neatly holding the handheld unit and its OBD2 cable, and another for the OBD1 cable and a selection of adapters. Innova also includes batteries to get you started right away, alongside a quick start guide. While the included manual gets you through the basics, Innova directs users to their website for a more comprehensive digital manual. Connecting the cables to the scanner head is straightforward. The OBD2 cable is a single, unified piece, while the OBD1 setup utilizes a generic cable paired with interchangeable adapters. The scanner features a blue backlit monochrome LCD display, capable of showing approximately ten lines of data at a time. Navigating the system is done through nine push-buttons and three LED indicators. In terms of size, the Innova 3120D is comparable to a standard television remote, making it easy to handle and store.
User Interface and Navigation: Simplicity vs. Efficiency
The button interface on the Innova OBD2 3120D presents a mixed bag. Navigation primarily relies on UP and DOWN buttons. While this keeps things simple, scrolling through lengthy lists, which are common in diagnostic menus, can become tedious, requiring multiple button presses to reach a desired selection in the middle of the list. This design choice prioritizes simplicity but sacrifices some efficiency in user interaction. Adding to this, the DTC (Diagnostic Trouble Code) display screen has a dedicated DOWN navigation button, separate from the main UP/DOWN buttons which then are repurposed to scroll through the potentially lengthy descriptions of the DTCs themselves. This can initially feel somewhat disjointed and requires a slight learning curve to become fully comfortable with the navigation logic.
OBD1 Performance on 94-95 F-Cars: A Critical Flaw
For owners of 94 or 95 F-body cars (like Camaros and Firebirds) equipped with the LT1 engine and OBD1 systems, the Innova OBD2 3120D, despite claiming compatibility, unfortunately falls short. To thoroughly assess its OBD1 capabilities on these vehicles, we conducted tests on a 94 LT1 PCM bench setup, comparing its readings against known accurate tools: a Tech 2 clone and Scan9495 PC software.
The results were disappointing. When connected to a perfectly functioning LT1 PCM with no trouble codes present, the Innova OBD2 3120D incorrectly reported a long list of false DTCs: 45, 44, 43, 42, 41, 55, 54, 53, and 52. Each of these incorrect codes came with a description, further misleading the user into believing there were actual issues. In reality, the scanner should have indicated “No codes.” To further validate the issue, we deliberately introduced a trouble code 22 into the PCM. Instead of simply adding code 22, the Innova 3120D displayed an incorrect added DTC 34, compounding the initial misdiagnosis.
Alt Text: Innova 3120 OBD2 Scanner Kit components laid out, highlighting the handheld unit, OBD2 cable, OBD1 cable, and adapters.
Root Cause Analysis: Data Misinterpretation
To understand why the Innova OBD2 3120D failed in OBD1 testing on these specific vehicles, we employed a data sniffer to monitor the communication line between the scanner and the PCM. This analysis revealed that the scanner was indeed sending correct data requests, and the PCM was responding with accurate data. The problem lies within the Innova 3120D’s interpretation of the data it receives.
Extensive testing, cycling through various vehicle year settings (93, 94, and 95) on the scanner, revealed the likely culprit: the Innova 3120D was incorrectly applying data interpretation protocols intended for different vehicles. Specifically, it appeared to be using the data stream definition A219, designed for 4.3L (LB4), 5.7L (L05), and 7.4L (L19) engines found in Type C, K, G, and P light/medium-duty trucks. This mismatch in data interpretation explains why the scanner was reporting a consistent set of incorrect DTCs. For instance, data bits intended for “Heated Windshield Request ON/OFF” in the 94 F-car data stream were being misinterpreted as DTC 45, which corresponds to a different parameter in the truck data stream.
While some DTCs could be cross-referenced due to overlapping bit positions, this workaround is severely limited. Much of the data stream contains information not shared between the F-car and the truck profiles, making a comprehensive conversion table impractical. Furthermore, the displayed incorrect DTCs can even fluctuate based on factors like gear selector position, as the data bits in those locations represent dynamic vehicle parameters.
Alt Text: Close-up of the Innova 3120 handheld scanner display showing diagnostic menu options, emphasizing the user interface for code reading.
OBD1 Code Erasing: Another Limitation
Another significant limitation for 94-95 F-car OBD1 systems is the Innova OBD2 3120D’s inability to erase trouble codes. When attempting to clear codes for these vehicles, the scanner simply displays instructions to follow the manufacturer’s procedure – which typically involves disconnecting the battery or pulling a specific fuse – essentially bypassing its supposed code clearing function.
OBD2 Potential: To Be Further Evaluated
The original article suggests that the Innova 3120D’s OBD2 functionality may be more reliable. However, this review focused primarily on its advertised OBD1 compatibility with 94-95 F-cars, where it demonstrably underperforms. A comprehensive evaluation of its OBD2 performance would require separate testing and is beyond the scope of this focused assessment.
Conclusion: Proceed with Caution for OBD1 F-Cars
The Innova OBD2 3120D scanner presents itself as a versatile diagnostic tool, supporting both OBD1 and OBD2 systems. However, our testing reveals a critical flaw in its OBD1 performance specifically with 94 and 95 F-body cars. The scanner’s misinterpretation of data leads to false DTC readings and an inability to clear codes for these vehicles.
While the Innova OBD2 3120D may offer value for newer OBD2 compliant vehicles, owners of 94-95 F-cars should exercise extreme caution. For accurate diagnostics on these classic machines, tools like a Tech 2 or software like Scan9495 remain more reliable and trustworthy options. Until Innova addresses this specific OBD1 incompatibility, it is difficult to recommend the 3120D for owners of these particular vehicles seeking accurate and dependable diagnostic capabilities.
