FAQ - Frequently Asked Questions

Q. I've confirmed my car has a MAF sensor, now I need an OBD-II Bluetooth adapter - which do you recommend?

A. ecoTRX apps are designed to be compatible with the ELM Electronics 327 OBD translator chip, which is used in the majority of OBD-II Bluetooth adapters. However, there are many brands of OBD-II Bluetooth adapters and we have not tested compatibility with all varieties. We recommend two of the most popular models on Amazon - the BAFX and the AGPTek. Based on our testing, you may want to consider the following points for each:


  • Claims tighter conformance to ELM protocol for wider vehicle/signal compatibility
  • Top mounted LEDs which are easier to read with horizontal OBD port vehicles (i.e. under steering wheel)


  • Shorter, which minimizes chance of interference with door, or knees
  • Front-mounted LEDs which are easier to read with vertical OBD port vehicles
  • Lower price
You can also search the Amazon reviews for these products to see if others have used them with your specific vehicle type.

Q. I don't see my OBD-II device in the ecoTRX Bluetooth Devices list of the Settings menu?

A. Please check to ensure that you have followed the OBD-II device manufacturers instructions for initial pairing with your Android phone. You may also need to refer to the Android phone instructions for bluetooth device paring as it varies by model and OS version.

Q. How do I "share and compare" my ecoTRX tank MPG results on the EPA My MPG site?

A. If you do not already have an account on the My MPG site, you can sign up using these steps (this is easier to complete on a laptop/desktop browser) or skip to step 5 if you already have an account:

  1. Go to My MPG portion of www.fueleconomy.gov at this link and create a new account - this will require email verification
  2. at My MPG page, go to My Garage and add your vehicle
  3. click My Fuel Purchases for your vehicle
  4. at the Fuel Purchase Customization prompt, select "recording the miles driven since last fillup" and "driving conditions", then press continue, then logout of the site
  5. go to the ecoTRX Settings page and enter your My MPG username and password to enable pushbutton tank result reporting
  6. when you fill up, go to the ecoTRX tank list page and press the "Start a New Tank" button

Q. Why does ecoTRX not show any trip update information after I start a new trip and heard "Bluetooth connected"?

A. Some phones/OBD devices do not always shut down their prior connections in a predictable fashion. If this happens, you may need to exit ecoTRX and restart the app and a new trip.