For anyone diving into DIY car maintenance or simply wanting to understand their vehicle better, having a reliable OBDII scanner is essential. Initially, like many, I started with a budget-friendly option: a $50 OBDII scan tool from Harbor Freight. It proved to be a surprisingly capable shop tool for basic diagnostics. However, the need for real-time monitoring while driving soon arose, leading me to explore the world of ELM327 based scanners.
The ELM327 Bluetooth OBDII dongle is a popular choice for its affordability and compatibility with smartphones. I picked up a generic ELM327 Bluetooth dongle for under $20 and paired it with my Android phone and Nexus 7 tablet. Using freely available apps, it worked seamlessly. It’s worth noting that if you’re in the Apple ecosystem, Bluetooth ELM327 dongles won’t work due to iOS limitations. For iPhones and iPads, a Wifi OBDII dongle is necessary. I invested in a Wifi version as well, and it functioned perfectly with both my iPhone and iPad, again using various free apps.
While these dongles are great for on-the-go diagnostics and code reading, for a more permanent monitoring solution, I opted for a dedicated device: the UltraGauge wired unit. Priced around $80 (though I recall paying slightly less previously), it offers continuous data display without needing to tie up a smartphone. UltraGauge also offers a wireless version for smartphone integration, but I preferred a standalone unit for dedicated monitoring during longer drives. My UltraGauge setup provides digital readouts for speed, instantaneous MPG, trip MPG, remaining fuel in gallons, miles to empty, and coolant temperature. While some of this information is available on the car’s instrument cluster and onboard computer, the UltraGauge allows for simultaneous viewing of multiple parameters. You can customize the display with up to 8 readings per page and navigate through 7 pages, although I find the 6-readout display with 2 larger and 4 smaller readings more practical than cramming in 8 small ones.
One significant advantage of a digital coolant temperature readout, like the one on the UltraGauge, is its precision compared to the often non-linear and compressed coolant dial on many instrument clusters. The digital display allows you to observe the exact temperature fluctuations, making it easier to monitor thermostat operation and overall cooling system performance. Beyond real-time monitoring, these scan tools, including basic models potentially found at Harbor Freight, are capable of reading and clearing diagnostic trouble codes. While the basic Harbor Freight scanner I initially used displayed numeric codes without text descriptions, this is where your smartphone and readily available apps come in handy for code translation.
This capability proved invaluable during an incident where my wife’s relatively new Nissan Altima experienced a transmission failure. Stranded and needing assistance, I brought my UltraGauge to the location. Upon connecting it, the code P0750 was immediately displayed. A quick lookup on my phone revealed it to be a transmission solenoid issue. Calling the Nissan dealer, they confirmed they were aware of potential transmission problems in that model. They promptly arranged for a tow truck, a rental car, and were prepared to address the issue upon our arrival, even late in the day. This experience underscored the practical benefits of having an OBDII scan tool readily available, whether it’s a basic model from Harbor Freight or a more advanced unit like the UltraGauge, for both routine checks and unexpected situations.
