314200 - Flex Fuel LGT/OBXT 05-09

314200 - Flex Fuel LGT/OBXT 05-09

Legacy GT 2005 - 2009

Outback XT 2005 - 2009

Congratulations on your purchase of the COBB Tuning Flex Fuel Kit! The following instructions will assist you through the installation process. Please read them BEFORE beginning the install to familiarize yourself with the steps and tools needed. If you feel you cannot properly perform this installation, we HIGHLY recommend you take the vehicle to a qualified and experienced automotive technician.

IMPORTANT! Installing this kit will require custom tuning or utilizing an appropriate Stage Power Package map if you have a matching mechanical configuration. Please consult with COBB or an authorized ProTuner in your area if you have any questions!

Table of Contents

Parts List

  • Firewall to Fuel Pressure Regulator Line
  • Fuel pressure regulator to Ethanol Content Sensor line
  • Ethanol Content Sensor to Fuel Rail line
  • Flex Fuel Bracket and Strap
  • Ethanol Content Sensor
  • 2 x 4x10mm hex screw
  • Flex Fuel Harness and Module (3-pin)
  • Rubber Isolator
  • Hex Nut
  • M6 x 16mm Socket head cap screw

Tools Needed



Hand Tools

Stock Component Removal

  1. Park your car in a flat, level area and allow it to cool down.

  2. Using your trim-tool remove the four clips holding the engine cover down.


  3. Utilize a 5/16" fuel line disconnect tool and disconnect the fuel lines from the engine and firewall sides.  If equipped you may need to remove these covers.


  4. Locate the fuel line assembly, it's rather large because it includes the fuel pressure regulator.  Pop the center line freefrom the clips and unplug the vacuum line.


  5. Undo the two vertical bolts holding the assembly to it's bracket.



  6. Remove the two bolts holding the bracket onto the strut tower.

Ethanol Content Sensor Installation.

  1. Using a 10mm socket undo the battery terminals starting with the ground terminal first.

  2. Undo the two 10mm bolts on the battery tie down and remove the battery from the car.

  3. Install the bracket and ethanol content sensor on the lower fuse box bracket as shown.

Fuel Line Installation

  1. Remove the top bolt of the remaining bracket and replace it with the provided rubber Isolator.

  2. Install the replacement OEM pressure regulator with the provided hex nut and tighten using your 10mm wrench.  You'll want the vacuum actuator on the regulator to be down.

  3. Using the short line with the straight fitting, install this between the lower port from the firewall and the fuel pressure regulator, making sure to pop the hose clamp on the line first.

  4. Install the other line in-between the regulator and ethanol content sensor making sure to add the clamp before installing..


  5. Run the last 90-degree line from the ethanol content sensor up to the bottom port of the fuel rail.

  6. Route the straight line from top port on the engine side to the top port on the firewall side.

  7. Reinstall the battery and turn the key-on and check for leaks.

Flex Fuel Module Installation

Installation of COBB Flex Fuel Module

The COBB Flex Fuel Module is designed to be bolted to the inter-cooler support bracket and plugged into the COBB Ethanol Sensor, in-line with the factory Rear O2 sensor and Tumble Generator Valve (TGV).

The Rear O2 connector obtains 12V power, and does not alter the O2 sensor signal going to the ECU. The TGV connection allows the motor signals to pass through for those still using the factory TGV's, however the feedback normally used to check TGV position is used to transmit Ethanol content data to the ECU (Engine Control Unit).

Mounting location may vary by customer/ installer preference, however it is recommended to seal any un-used connections from water intrusion, ideally by using the proper connector mate and using plugs to seal the mating connector.

  1. Bolt the Flex Fuel module to the inter-cooler support bracket using the included bolt. Straighten the cables so that they aren't crossed over each other.

  2. Pass the Flex Fuel Connector through the factory hoses and wiring harnesses and plug it into the Ethanol sensor. Ensure there is no strain on the connector, wiring, or the module.

  3. Pass the TGV Connector through the factory hoses and harnesses to the TGV position sensor on the driver's side of the vehicle toward the rear of the engine. Especially if on a lift, you may find this easier to do from the bottom of the vehicle where there's a clear path to the TGV. Ensure there is no strain on the TGV connector, wiring, or the module.

  4. Route the Rear O2 Connector to the bottom of the engine bay, then suitably raise and support the vehicle. Never work on a vehicle supported by a jack alone.

  5. Connect the Rear O2 Connector between the factory O2 sensor harness and the O2 Sensor connector.

  6. The O2 connector harness has extra length to work on a variety of vehicle configurations. Using the included zip-ties, secure the harness to the metal lines on the underside of the vehicle and in the engine bay. Ensure that the harness will not make contact with moving parts like the steering column, exhaust parts, and has sufficient slack between the engine and lines as well as lines and harness so that there is no strain as the engine moves.

  7. Power your car on but don't start it quite yet.  Go under the hood and check for leaks from the fuel lines.

  8. Flash an appropriate map for your modifications.

  9. Go out and enjoy!


Calibration Map Notes for Subaru Vehicles

Helps to figure out which map you should be on given the parts installed to your car 

Error rendering macro 'excerpt-include' : You can only link to a page or blog post.

Copyright 2023 © COBB Tuning Products LLC. All Rights Reserved. | www.cobbtuning.com