Cobb CAN Flex Fuel Upgrade (Module/Harness/Bracket/Ethanol Sensor) - 2018-2021 Subaru WRX

Upgrade Kit — Add Flex Fuel to Your Existing Cobb Setup

The Cobb CAN Flex Fuel Upgrade Kit for the Subaru Models adds flex fuel capability to an existing Stage 1+ package without buying a full new kit. The CAN ethanol sensor reads the fuel's ethanol content in real time and sends that data directly to the Accessport, which adjusts boost, fuel, and ignition timing automatically based on what's in the tank. Run 91 octane on a daily commute and switch to E85 at the track — the system adapts without a retune.

How the CAN System Works

Traditional flex fuel setups require the sensor signal to be wired into the ECU and require a custom tune for each ethanol blend. The Cobb CAN system is different — the ethanol sensor communicates through the same CAN bus the Accessport already monitors, and the Accessport firmware handles the tune adjustment automatically based on the sensor reading. The result is a truly seamless flex fuel experience where the car runs the optimal tune for whatever is in the tank at any given moment.

Plug-In CAN Connection — No ECU Wiring Required

The Cobb CAN Flex Fuel kit connects to the vehicle's existing CAN bus through a simple plug-in harness — no splicing into the ECU, no custom wiring. The Accessport V3 is required to use this kit, as it's the device that reads the CAN data and displays or acts on it. Installation is straightforward and reversible.

Key Features

• Platform: Subaru Models
• Plug-in CAN bus connection — no ECU wiring or splicing required
• Requires Cobb Accessport V3 for sensor data display and tune adjustment
• Real-time ethanol content detection — automatic tune adjustment via Accessport
• Upgrade kit — adds flex fuel to existing Stage 1+ Cobb setup
• Fully reversible installation

Fitment Notes

• Platform: Subaru Models
• Requires Cobb Accessport V3 — does not work without Accessport
• Confirm MT vs CVT compatibility by SKU before ordering

Straight From Subispeed

The Cobb CAN system is the right approach to flex fuel on the Subaru — plug-in installation, Accessport integration, and automatic tune adjustment without a separate fuel management system or wiring harness. If you are on a Cobb tune and considering E85, the CAN Flex Fuel kit is the cleanest way to do it.

What's Included

• Cobb CAN Flex Fuel Kit — Subaru Models
• CAN bus harness and sensor
• All mounting hardware

About Cobb Tuning

Cobb Tuning has been developing performance parts and tuning solutions for Subaru vehicles since 1999. Based in Austin, Texas, Cobb built their reputation on the Accessport — the most widely used Subaru ECU tuning device on the market — and expanded that into a full ecosystem of intake, exhaust, drivetrain, and engine bay accessories engineered specifically for the platforms they support. Every Cobb product is developed in-house and validated on their own test vehicles before it reaches customers. Subispeed carries the full Cobb catalog because their engineering standards and platform-specific development process consistently produce parts that work exactly as advertised.