Frequently Asked Questions
Everything you need to know about the Flextron app and Flextron ECA sensor module.
Everything you need to know about the Flextron app and Flextron ECA sensor module.
Flextron is a free mobile app for iOS and Android that connects to the Flextron ECA flex fuel sensor module over Bluetooth Low Energy (BLE). It displays real-time ethanol content (0–100%) and fuel temperature, logs sessions, shows nearby E85 stations on a map, and allows full CAN Bus configuration of the sensor.
No account or registration is required.
Yes. Flextron is completely free to download and use with no in-app purchases or subscription fees.
Any smartphone with Bluetooth Low Energy (BLE 4.0+) support running:
Most smartphones released after 2015 are compatible.
The dashboard shows:
Start recording from the Log screen to capture timestamped ethanol and temperature readings at regular intervals. Sessions are saved locally on your device and can be exported to CSV for use in spreadsheets or tuning software.
Yes, but only while the Map screen is open. GPS is disabled as soon as you leave the Map screen to preserve battery life. The app will request location permission the first time you open the map.
The dashboard and logging features require a connected Flextron ECA module. However, the E85 station map works independently without a sensor connected.
Yes. Flextron supports full dark and light themes and follows your phone's system preference automatically. You can also override this manually in the app Settings.
The Flextron ECA ships as a complete, ready-to-install kit:
The ethanol sensor is installed inline in the vehicle's fuel feed line between the fuel pump and the fuel injectors. The included fittings are AN-compatible and connect directly to the sensor body.
The following platforms are natively supported out of the box:
Any platform that reads CAN Bus can be configured to work by setting a matching message ID and frame type.
The module is powered directly from the vehicle's 12 V electrical system via the included wiring harness.
No. Flextron ECA uses Bluetooth Low Energy (BLE) advertising, which does not require traditional pairing. The app connects automatically when the sensor is within range and the vehicle is powered on.
Effective range is typically 5–10 metres depending on obstructions, phone placement and environmental conditions. The sensor is designed for in-vehicle use with the phone inside the car.
On Android 12+, the app requires Nearby Devices (Bluetooth Scan & Connect) permission. On older Android versions, Location permission is required by the OS for BLE scanning. On iOS, Bluetooth permission is requested on first launch.
Open the CAN Bus Settings screen in the app while connected to the sensor. Enter the desired message ID in hexadecimal (e.g. 0x180) and tap Save. The setting is immediately written to the sensor's non-volatile memory and persists across power cycles.
The following update rates can be selected: 4 Hz, 10 Hz, 50 Hz, 100 Hz, 250 Hz, 500 Hz, 1000 Hz.
Standard (11-bit) frames work with the vast majority of tuning platforms and ECUs. Use Extended (29-bit) only if your specific ECU or tuning software explicitly requires it. When in doubt, use Standard.
Yes. All CAN Bus parameters (message ID, frame type, update rate, bus speed) are stored in the sensor's non-volatile flash memory and are retained indefinitely even without power.
Automatic (recommended): When a newer firmware version is available, a banner appears on the Device screen three seconds after connecting. Tap Update — the app downloads and installs the firmware automatically over Bluetooth.
Manual: You can also flash a firmware file from your device storage:
.bin firmware file from Gritron.bin file from your device storageYes. While connected to the sensor, go to Settings → Change Device Password. Enter a new 4–6 character PIN and confirm. The change is sent over Bluetooth and the device acknowledges acceptance. No USB flashing required.
The app validates firmware files before transfer to prevent flashing corrupt or incompatible images. A file will be rejected if:
0xE90xEAMake sure you are using a genuine Flextron ECA firmware file provided by Gritron.
Ethanol readings can be influenced by fuel temperature. Ensure the sensor has been running for at least 30 seconds after the engine starts to allow the reading to stabilise. If readings remain unusual:
For technical support, export a log file from the app (Logs → Share) and contact Gritron via the official channels listed on the Flextron website. Include your phone model, OS version and a description of the issue.