331200 - Flex Fuel Forester XT 05

331200 - Flex Fuel FXT 2005

Forester XT 2005

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 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)
  • 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 off.
  2. Locate your fuel lines at the manifold and the firewall.  Choose one end to disconnect first and surround it with something to absorb the fuel that will come out when you undo the lines. 


  3. At this point you can go ahead and remove the remaining fuel lines, leaving the vent tube attached to the barbed fittings. The lower line (feed) is the only one you really need to disconnect, however removing both can help you get a little bit more room to work in.


  4. Remove the furthest forward injector cover bolt on the driver's side (USDM) using a 12mm wrench


  5. Bolt the flex fuel module in it's place using the supplied socket headed cap screw and your 6mm allen bolt.  Make sure to put the ground cable back underneath and that it's clocked in a way that it sits flat and doesn't get broken off.


  6. Route the o2 sensor line towards the back behind the intercooler either with the other harnesses or over the top.

    Make sure to avoid any heat sources or anything that may pull on the wiring when routing the wires.


  7. Route the brown connector to the ethanol content sensor the same direction as the o2 sensor harness making sure to go under the fuel lines.


  8. Unhook the driver's side 3-pin TGV connector on the front of the cylinder head.

  9. Plug the 3-pin connector from the flex fuel module into the newly removed harness.


  10. Using your 10mm socket and extension, remove the two bolts holding the fuel line support bracket and reinstall with just the lower half in place.


  11. Moving to the other 12mm injector cover bolt, remove it with your socket.

  12. Bolt the ethanol content sensor assembly in place.  Make sure to angle it down slightly in the front.

  13. Taking the line with two straight connectors, attach the line to the ethanol content sensor, and the lower feed lien coming from the firewall.


  14. Connect the remaining line with the straight connector on the ethanol content sensor.  If installing the fuel pressure sensor adapter you'll put it on the output side of the ethanol content sensor.


  15. Create a small loop and hook the 90 degree connector to the top port of the fuel rail.  If using the fuel pressure sensor adapter you may need to gently push down on the AC line in order to get it out of the way of the line and minimize chafing.


  16. With the lines in place make sure the existing return line isn't rubbing anywhere on the ethanol content sensor bracket.  Loosening the clamps near the fuel damper can allow you to spin the line slightly to gain more clearance in some spots.  Make sure there is adequate space so that it won't rub on anything.

  17. Push down all of the quick connect clips and power the car on (Do not start) to ensure there are no leaks.

  18. Now safely lift and support your car.

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

  20. 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.

  21. Flash an appropriate map for your level of modifications and go out and enjoy!


Calibration Map Notes for Subaru Vehicles

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