Spool Performance BMW B58 E85 Flex Fuel Ethanol Content Sensor & Bluetooth BLE Analyzer Gauge/Reader Kit – Fuel Composition Monitor App (iOS/Android) – F-Series M140i M240i 340i 440i (F20 F21 F22 F23 F30 F31 F32 F33 F36) – SP-ECA-B58

Spool Performance Ethanol Content Monitor for BMW B58

Dial in safe power on your B58 turbo straight‑six with Spool Performance’s wireless fuel composition monitor. This BLE (Bluetooth Low Energy) module streams live alcohol percentage and fuel temperature to your smartphone, letting you run E30, E50 or full corn fuel with confidence. It’s the go-to flex-fuel reader for F-series 1 Series, 2 Series, 3 Series and 4 Series models running the legendary 3.0-litre B58.

We use this kit on our own cars and our customers rate it highly for accuracy and ease of use. If you’re blending pump petrol with ethanol, this is the must-have way to verify exactly what’s in your tank before you load a map or push for more boost.

Why you need a fuel composition sensor on a tuned B58

Real-world E-content at the pump can swing wildly. Fuel labelled “E85” can be anywhere from roughly E51 to E85. That variability can upset timing, reduce performance and increase knock risk if your calibration expects higher alcohol content than you actually have. A live ethanol percentage readout removes the guesswork so you can blend precisely, log confidently and keep your straight‑six happy on the road or track.

Key advantages

• Live ethanol percentage and fuel temperature straight to your phone
• BLE connection for minimal battery drain and quick pairing
• Companion app includes a simple blend calculator for E30, E50, E85
• Works with a GM-type ethanol sensor for stable, repeatable readings
• Purpose-built for BMW B58 platforms: M140i, M240i, 340i, 440i
• Robust, proven and cost-effective for flex-fuel and hybrid turbo setups

App functions

• On-screen E-content percentage and fuel temperature (Fahrenheit)
• Mix calculator to hit your target blend every time
• Free to download and use, even for estimating blends without hardware

Perfect for

• B58 ethanol content monitoring with remaps, custom tunes and data logging
• E30, E50 and E85 blends for performance driving
• Safeguarding timing and knock control on modified engines

Vehicle compatibility

B58 engine models:

1 Series

• F20 LCI (09/2015 - 06/2019): M140i and M140ix
• F21 LCI (09/2015 - 06/2019): M140i and M140ix

2 Series

• F22 (09/2015 - 06/2017): M240i and M240ix
• F22 LCI (09/2016 - 12/2019): M240i and M240ix
• F23 (09/2015 - 06/2017): M240i and M240ix
• F23 LCI (10/2016 - 12/2019): M240i and M240ix

3 Series

• F30 LCI (10/2014 - 10/2018): 340i and 340ix
• F31 LCI (10/2014 - 06/2019): 340i and 340ix
• F34 GT LCI (10/2014 - 2019): 340i and 340ix

4 Series

• F32 (2013 - 02/2017): 440i and 440ix
• F32 LCI (05/2016 - 12/2019): 440i and 440ix
• F33 (03/2015 - 02/2017): 440i and 440ix
• F33 LCI (05/2016 - 12/2019): 440i and 440ix
• F36 Gran Coupé (03/2015 - 02/2017): 440i and 440ix
• F36 Gran Coupé LCI (05/2016 - 12/2019): 440i and 440ix

Part number

SP-ECA-B58

Fitting and support

Want it installed by specialists? MJ Modifications in Warwickshire offers professional fitting. Request a quote at info@mjmodifications.co.uk.

Compatibility check before dispatch

We verify fitment prior to shipping. Provide your UK registration or the last 7 of your VIN at checkout and we will confirm compatibility.

Manufactured by

Spool Performance

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