The Innova 3120 Obd2 scanner has garnered attention from numerous users, particularly those working on 94 or 95 F-body vehicles. Reports of operational problems with these specific models prompted an in-depth evaluation of the Innova 3120. This review delves into the scanner’s performance, specifically focusing on its compatibility with OBD1 systems in these classic F-cars, to provide potential users with a comprehensive understanding of its capabilities and limitations.
The Innova 3120 OBD2 scanner arrived packaged in two practical black zippered plastic cases. One case neatly contained the handheld unit and its OBD2 cable, while the other held the OBD1 cable and various adapters, catering to a range of vehicle diagnostic needs. The inclusion of batteries upon unboxing is a convenient touch, allowing for immediate use. However, the accompanying physical manual is notably brief, essentially directing users to download the complete manual from the innova.com website for detailed instructions and functionalities. The scanner itself features a connector port designed to accommodate the interchangeable cables. The OBD2 cable is a single, unified piece, whereas the OBD1 setup utilizes a universal cable paired with interchangeable adapters, offering versatility across different OBD1 systems.
The Innova 3120 is equipped with a blue backlit LCD monochrome display, capable of showing approximately ten lines of diagnostic data at a time. Navigating the scanner’s functions is done through nine push-buttons and three LED indicators. In terms of size, the unit is comparable to a standard large television remote control, making it reasonably easy to handle and operate within the engine bay or vehicle interior.
However, the button interface presents usability challenges. The reliance on only UP and DOWN buttons for menu navigation proves cumbersome, especially when scrolling through lengthy lists of options. Selecting an item positioned in the middle of a list requires multiple button presses, slowing down the diagnostic process. This design quirk is further amplified in the DTC (Diagnostic Trouble Code) display screen, which features only a single, dedicated DOWN navigation button. The standard UP and DOWN buttons are repurposed for scrolling through the potentially lengthy descriptions of the DTCs, rather than for navigating between different DTC codes themselves, leading to a less intuitive user experience.
This review will now concentrate specifically on the Innova 3120’s performance when used with OBD1 systems in 94 and 95 LT1 F-cars. For comparative analysis and validation, a Tech 2 clone and the Scan9495 PC application were utilized as benchmarks, representing professional-grade diagnostic tools and specialized software for these vehicles.
Unfortunately, initial testing revealed significant shortcomings. Contrary to the listed vehicle compatibility, the Innova 3120 OBD2 scanner does not function correctly with 94 or 95 F-cars equipped with OBD1 systems. When connected to an LT1 PCM (Powertrain Control Module) test bench that was intentionally free of any fault codes, the scanner erroneously reported a substantial list of DTCs: 45, 44, 43, 42, 41, 55, 54, 53, and 52. Each of these phantom codes was accompanied by a description appropriate to the number, yet they were entirely false readings. Under normal circumstances, a “No codes” message should have been displayed. To further investigate, a genuine fault code (DTC 22) was deliberately introduced to the PCM. In response, the 3120 scanner added an additional incorrect code, DTC 34, further demonstrating its unreliability with this specific application.
Alt Text: Innova 3120 OBD2 scanner kit laid out showing handheld unit, OBD2 cable, OBD1 cable, adapters, and carrying cases, highlighting the complete set for vehicle diagnostics.
Data line analysis using a data sniffer confirmed that the Innova 3120 OBD2 scanner was indeed sending correct data requests, and the PCM was accurately returning the expected data. The core issue lies within the scanner’s internal software – it is misinterpreting the data received from the 94-95 F-car OBD1 system. Extensive testing was conducted, cycling through virtually every combination of vehicle year settings available on the 3120 for 1993, 1994, and 1995. This exhaustive process aimed to identify a potentially mislabeled or alternative vehicle selection that might yield correct readings for the 94/95 F-car. The investigation revealed that the scanner was incorrectly applying the data interpretation protocol intended for 4.3L (LB4), 5.7L (L05), and 7.4L (L19) engines found in Type C, K, G, and P light/medium duty trucks (as defined by data-stream definition A219).
Every piece of diagnostic information, when forcing various DTCs on the test bench, consistently correlated with the erroneous DTCs displayed by the Innova 3120 based on this incorrect truck profile. Notably, certain data bit positions within the OBD1 data stream, intended for specific parameters in the 94 F-car, aligned with the positions of the nine false DTCs previously listed, which are relevant to the truck profile. For instance, in the 94 F-car data stream, the bit representing the “Heated Windshield Request ON/OFF” status occupies the same position as the DTC 45 set bit in the truck’s data profile.
Unfortunately, this cross-referencing approach is limited, applicable to only approximately ten DTCs. This limitation arises because the OBD1 data stream also contains other types of information interspersed with the DTC data, which do not consistently align with the data structure used for these alternative vehicle profiles. Consequently, creating a comprehensive DTC conversion table as a practical workaround to translate the misread codes would be of limited utility and reliability. Further investigation into alternative solutions or compatible vehicle selections within the scanner’s menu is ongoing. If any users have discovered a vehicle setting within the Innova 3120 that provides accurate readings for 94-95 F-cars, sharing this information would be invaluable.
It’s important to note that the specific false DTCs reported may vary beyond the initial list of nine, as the data bits in those positions can represent dynamic vehicle parameters that change during operation. For example, the displayed DTCs can fluctuate depending on the position of the gear selector, highlighting the scanner’s misinterpretation of even basic vehicle state data.
Regarding the ability to clear trouble codes on these specific F-cars, the Innova 3120 OBD2 scanner proves ineffective for OBD1 systems. Upon attempting to erase codes, the unit displays an instruction to manually follow the manufacturer’s recommended procedure, such as disconnecting the vehicle’s battery or pulling specific fuses, rather than performing the code clearing function electronically, as expected of a modern scan tool.
While the OBD1 functionality for 94-95 F-cars is demonstrably flawed, the OBD2 capabilities of the Innova 3120 scanner remain to be thoroughly assessed. Future evaluation will focus on its performance with OBD2 compliant vehicles to provide a more complete picture of its diagnostic utility across different OBD standards. For owners of 94-95 F-cars specifically seeking an OBD1 diagnostic tool, the Innova 3120 in its current form is not recommended due to its inaccurate readings and inability to erase codes on these vehicles.
