COBB Subaru NexGen Flex Fuel Ethanol Sensor Kit – 2015-2021 Subaru STI

Cobb Subaru NexGen Flex Fuel Ethanol Sensor Kit — 2015-2021 Subaru STI

The Cobb CAN Flex Fuel Upgrade for the 2015-2021 Subaru WRX STI installs the CAN-based ethanol content sensor in the fuel delivery system, enabling the Accessport to measure ethanol percentage in real time and automatically adjust calibration for any fuel blend from 93 octane through E85. Requires an Accessport V3 with the appropriate CAN Flex Fuel maps.

DETAILS

• Platform: 2015-2021 Subaru WRX STI
• CAN ethanol sensor: measures actual ethanol content in real time
• Enables Cobb CAN Flex Fuel OTS maps for dynamic calibration
• Requires Accessport V3 with appropriate CAN maps
• Sensor kit only — does not include Accessport

How CAN Flex Fuel Works

Cobb’s CAN Flex Fuel system uses an ethanol content sensor in the fuel line to measure the actual ethanol percentage in real time and communicate it to the Accessport via CAN bus. The Accessport ECU map adjusts fueling, ignition timing, and boost targets automatically based on the measured content — no manual map switching required. Run any blend from 93 octane through E85, and the system calibrates itself for whatever is in the tank.

Ethanol Benefits and System Installation

Ethanol provides two performance advantages: a significantly higher effective octane rating that allows more aggressive ignition timing, and a high latent heat of vaporization that cools the intake charge. Together these allow the CAN Flex Fuel OTS maps to target higher boost and more aggressive timing on E30 or higher blends versus the equivalent 93-octane gasoline maps, producing a meaningful power increase when ethanol fuel is available.

What’s in the Box

• CAN flex fuel ethanol sensor
• Fuel line fittings
• Instructions

Why Choose Cobb Tuning

Cobb Tuning has been developing performance software and hardware for turbocharged enthusiast vehicles since 1999. Founded in Austin, Texas, Cobb built its reputation on the Accessport and expanded into a full catalog of hardware engineered to complement it. Every OTS map is developed in-house on real vehicles, and every hardware product is validated as part of a complete system — not sourced and sold in isolation. That integrated approach is why Cobb produces consistent, reliable results across the builds we see every day.

The RallySport Take

The CAN Flex Fuel sensor enables the Accessport to automatically adjust calibration for any ethanol blend without manual map switching. Requires Accessport V3 with the appropriate maps. Platform: 2015-2021 Subaru WRX STI.

Fitment

Year	Make	Model	Notes
2015-2021	Subaru	WRX STI	EJ257 MT — requires Accessport with CAN FF maps