S58 BMW M2 M3 M4 X3M X4M Flex Fuel Ethanol Content Sensor for E85 Fuel Monitoring

Run E85 with confidence. The BMS CANflex kit gives your S58 BMW a clean, accurate way to read ethanol content and send that data directly to your tune.

This complete S58 flex fuel kit (FFK), also known as an ethanol sensor kit, E85 sensor, flex fuel sensor, ethanol content sensor, fuel composition sensor, or flex fuel composition sensor, installs in about 30 minutes with the optional plug & play harness.

The CANflex ECA works as an ethanol content analyzer (ECA), E85 analyzer, and Bluetooth flex fuel analyzer in one compact system. It reads your fuel mixture using a genuine Continental® ethanol sensor and outputs the data through CANbus, Bluetooth, a built-in LED display, and 5v output for legacy support.

Perfect for S58 owners running E85, adding port injection, or wanting accurate real-time ethanol data for JB4, MHD, BM3, or EcuTek tuning.

CANbus via user selectable addressing for MHD, BM3, EcuTek, and JB4 integration

• Free CANflex Bluetooth app for iOS and Android
• LED display built into the head unit for quick visual readout
• 5v output for legacy support (older ECUs or non-CANbus JB4 integration)

Offered in both a plug and play harness and a universal harness. Manual transmission vehicles and BM3 require using the universal harness with posi-taps for CANbus.

Vehicle Fitment

• 2020+ S58 F97 X3M
• 2020+ S58 F98 X4M
• 2023+ S58 G87 M2
• 2021+ S58 G80 M3
• 2021+ S58 G82 G83 M4
• 2023+ S58 G82 M4 CSL

Complete S58 kit with CANflex includes:

• Genuine Continental® ethanol sensor
• BMS CANflex LED ECA for use with JB4, MHD, EcuTek, and BM3
• Stainless steel braided fuel lines with black nylon sheathing to protect engine bay components
• Custom fitting allowing easy addition of optional port injection lines via 1/8" NPT port
• Plug & play harness (optional)
• BMW/Supra Accessory Harness for S58/B58 motors

Download the free BMS CANflex app

Wiring diagram for the new BMS Bluetooth CANflex Harness

Red: (originally Red/Green) 12v switched power via fuse tap or posi-tap
Black: Chassis ground
Brown: (originally Orange) CAN-
Green: (originally Red/Blue) CAN+
Blue: 5V legacy output for input into JB4

Install Videos

Vehicle fitment