VB CAN Flex Fuel
- Brandyn Mowat
VB WRX CAN Flex Fuel
Congratulations on your purchase of the COBB Tuning VB WRX CAN Flex Fuel! 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.
Parts List
345650 Subaru CAN Flex Fuel Kit
346700 VB Fuel Pressure Sensor Kit
Tools Needed
Sockets
3/8"
3/8" ratchet
3/8" 12" extension
3/8" 6" extension
3/8" 10mm socket
3/8" 12mm socket (if removing intercooler)
3/8" 13mm socket
Hand Tools
Phillips head screwdriver
Flathead screwdriver
2.5mm Allen Key
3mm Allen Key
3/16” Allen Key (for NPT plug on fuel pressure adapter)
7mm Nut Driver
Trim removal tool
Wrenches
7/8” or 22mm Wrench (for fuel pressure sensor)
A Quick Message on Screw-in Connectors
The screw in wiring connectors we use for environmental sealing are specifically keyed to a certain direction to ensure all the pins are in the right spot. When in doubt gently press while slowly rotating the connector until it lines up, then press it in until the threads engage, then tighten the connector down finger tight.
Pre-Assembly
Locate the bracket, ethanol sensor and m4 screws.
On the back side of the sensor you can (but don’t need to) remove the backing from the double-sided tape. It’s main function is to cushion the sensor against the bracket rather than hold it in place, so it’s up to you.
Position the sensor with the strap onto the bracket with the wiring connector facing upwards. Then screw it in from the back side using a 2.5mm Allen wrench.
Install the fuel pressure sensor into the fuel pressure sensor adapter with a small dab of the provided thread sealer. You may want to test fit it on the car to make sure the sensors harness doesn’t get in the way of anything as things are quite tight. You’ll need to use a 3/16” Allen to remove the NPT plug in place, and a 7/8” or 22mm wrench to tighten the sensor down.
Gateway and Ethanol Sensor Mounting
Park your car in a flat level area.
With your car running, remove the fuel pump fuse and leave the car idling until it dies (this may take a while.) This should depressurize the fuel system to minimize the amount of fuel spilled.
Jack your car up and support it properly, you’ll need to get under it for step 16.
[Optional] Remove Top Mount Intercooler. While not necessary, it will allow you to get better access to the fuel lines, so If you’re having a hard time it might be worth the 5-10 minutes to remove and reinstall the intercooler. Check out our intercooler instructions for tips on removing the factory one Stock Intercooler Removal: VB WRX Intercooler Install
On the passenger’s side of the engine bay Locate the fuel line underneath the strange aluminum AC line loop. It should have a black retaining clip over the line.
On the end towards the front of the car, gently spread out the curved legs of the clip, this should release it from the fitting on the fuel line, and then it can be removed from the car.
Using your fingers or a flat bladed screwdriver, pull out the flat center portion of the blue clip to release the soft fuel line. It’s a good idea to have a cloth or absorbant pad there to catch any drips.
Repeat this process at the other end of the fuel line near the intake manifold.
Squeeze the tabs of the fuel line retaining bracket so it can be removed from the car.
Install the two standoffs onto the two studs sticking out from your firewall on the passenger’s side (above where the fuel line comes out) using a 13mm Socket or wrench.
Using the two provided bolts, install the gateway onto the bracket with a 10mm socket.
Plug the ethanol content sensor harness (brown connector) into one of the bottom two Sensor ports on the gateway and loop the harness down and around from the back of the bracket and up onto the ethanol content sensor. The bracket has two vertical slits on the gateway side you can slip a zip tie through to secure the harness.
Install the bracket with the sensor and gateway into the car over the two standoffs, securing it with the two supplied flange nuts. If you have an issue you can install the bracket with the ethanol sensor first, then bolt down the gateway.
Take the fuel line with two 90° fittings on it. One end has a smaller opening than the other. The smaller end will go over the factory fuel feed line on the car side, and the larger opening will go to the top port of the ethanol content sensor. Give each end a gentle tug to make sure they are securely in place. You can then zip tie the hose to the brake lines nearby.
Install the fuel pressure adapter onto the engine side of the fuel line. Then hook the smaller end of the remaining fuel line (straight fitting) onto the adapter pushing it all the way on and latching it closed before giving the whole assembly a gentle tug to make sure it doesn’t come off.
The other large 90° end of the fuel line will go to the bottom port of the ethanol content sensor.
Plug in the fuel pressure sensor harness and run the wire over to the other unused sensor port on the gateway.
Plug in the long vehicle harness for the gateway to the top left port of the gateway and screw it down. The harness can get routed behind the two wiring harnesses and down into the engine bay following the brake lines.
From underneath the car, locate the AC drain hose on the passenger’s side and remove the grommet. This is on the fire wall on the passenger’s side, right next to where the shift linkage is on the transmission.
Push the small connector end up into the hole above the drain line, then slip the hose into the large opening in the grommet on the harness. Then push the grommet into place on the firewall making sure the edges are evenly grabbing the metal. The grommet is deliberately placed on the harness to minimize any water intrusion, do not slide it up or down the harness.
Once that’s through, zip tie it out of the way (keep it far away from the CV axle please!)
In the passenger compartment, gently pull back the carpeting in the passenger’s footwell near the center of the car. You should see the wiring coming out. Route it up behind the center console and dash near the stereo.
Factory Gateway Bypass Installation
In order to add signal onto the CAN BUS of the car (and not mess with important functions like brakes or steering) we added components to allow you to integrate into the factory CAN module.
On the passenger’s side we’ll start by removingthe dash’s end cap. We recommend using a plastic tool do this and minimize scratching. Find a gap and gently pry outward
The upper dash rail will now need to come out, gently pull outward at first until it pops out and you can see the blue clips.
The black clips you see hooking into the dash are now holding that piece in place. To remove it slide the piece toward the center of the car and the hooks should release and allow you to remove the piece.
Remove the newly exposed two screws on the right hand side of the dash with a #2 Phillips screwdriver.
The trim around the screen should now come out, This includes the hood over the screen and the trip button which has an electrical connector on the back side that you’ll need to release in order to fully remove the panel.
This should leave you with a giant screen and 4 10mm bolts. Remove those bad boys with a socket and extension and do your best not to drop them. As they come out I like to put my finger over the flange of the bolt to hold it into the socket.
Now the fun part that will potentially give you some anxiety about scratching your screen! If you’re really worried cover it with saran wrap or blue painters tape. Cleaning the residue is better than scratching the screen. Either way we like to put the shifter into 6th gear to get it mostly out of the way, and then cover it with a soft cloth.
Gently pull outward on the stereo screen until you’re stopped by the first wiring harness (of many).
Take a picture of the connectors on the back of your stereo. No seriously, that way you can make sure you get them all back in again, yours may differ from ours if you have different options. To remove the connectors we typically press down on the release tabs with a screwdriver or trim tool. We take everything off of this first module as well as the one random connector at the top on the bracket.
Taking the connectors from the top module out should allow you to lay the stereo down against the shifter. You can do the rest of the job with it partially out of the way, or you can take the stereo completely out. If you want to do that continue on and remove all the connectors from the bottom module as well. (again, take pictures!)
This black module on the bottom of the newly opened gap is what you’re going to be working with next. This job can be done with it in the car, or you can pop out the two screws in the front and remove it form the car to do it more easily, as Captain Planet (He’s a hero) said, the power is yours!
Either way disconnect the wiring harness from the module.
Apply the vibration pad onto the bottom end of the module lengthwise, fairly close to the bracket.
The metal strap will go around the module from underneath close to the metal.
The module will get attached to the strap using the set allen screws and mount using the set of holes closest to the end with two connectors. (The end with the same factory connector as the stock module will be on that same end.)
Plug the smaller end of the bypass wiring harness into the module, then zip tie it through the middle hole of the module to hold it down and out of the way. The big connector goes into the stock CAN module.
Now the module can go back into the car (if removed). And the stock wiring harness can get plugged into the COBB module.
Going up the opposite side of the can harness, bring the COBB harness around from the firewall and install it into the remaining port on the module. (Shown outside of the car due to space constraints)
Everything can now go back together because you’re all done! Make sure to go slow and check to make sure you don’t have anything left unplugged (unless, like our car you had one plug not plugged in to anything from the beginning).
You’re all done! Go out and enjoy!
Related content
Copyright 2025 © COBB Tuning Products LLC. All Rights Reserved. | www.cobbtuning.com