Home » PRL Motorsports 2017+ Honda Civic Type-R FK8 Plug ‘N Play Flex Fuel Kit Install Guide

PRL Motorsports 2017+ Honda Civic Type-R FK8 Plug ‘N Play Flex Fuel Kit Install Guide

2017+ FK8 Honda Civic Type-R Plug ‘N Play Flex Fuel Kit

Install Time: 1 Hour


Install was performed on a modified application. Some hardware shown may be different than the hardware used on the stock vehicle.

Allow vehicle to cool completely prior to attempting installation.

PRL Motorsports is not responsible for any vehicle damage or personal injury due to installation errors, misuse, or removal of PRL Motorsports products.

PRL Motorsports suggests trained professional installation all PRL Motorsports products

Table of Contents

Here is a general list of what you should have received with our kit. Please unpack and verify that all components have been received prior to installation.

  1. (1) Pre-assembled flex fuel kit
  2. (6) Zip-ties

Recommended Tool List

  1. Ratchet (3/8” or ¼” preferred)
  2. Various extensions (3”,6”)
  3. 10mm socket
  4. Small pick or pocket screwdriver (flathead)
  5. Diagonal cutting pliers (side-cutters, snips, etc.)
  6. Safety Glasses
  7. Shop towels
  8. Floor jack
  9. Jack stands

Installation Guide

  1. Discharge the fuel pressure in the factory feed line.
  • Inside the driver’s compartment, located above the hood release in the interior fuse box. Using the factory tool remove the 20amp fuse in location 8.
  • Start the car (In some cases you may need to start the car with the fuel pump fuse installed if your car has been sitting for a period of time.)
  • Let the car idle until fuel pressure has dropped enough that the car stalls. (This may take a few minutes)
  • Place fuse in a safe spot until you are done with the installation
  • Let the car cool down to a comfortable temperature to work in the engine bay. A good idea would be to plan the install around lunch or even letting the car sit overnight.

2. Using a 10mm socket, loosen the negative terminal and remove. Tuck into engine bay out of the way.

3. Remove the (2) 10mm headed bolts on the factory fuel line bracket cover.

4. Depress tab and release the (3) fuel line holders using a pick or pocket screwdriver.

5. Remove the fuel line out of the clamp to gain access to the bolts behind it.

6. Use a 10mm socket to remove the (2) bolts holding the fuel line bracket to the firewall.

7. Remove the (2) safety clips from the factory fuel line connectors. Pull out and rotate 90 degrees to the line, then slip them out of the existing slot.

8. Wearing safety glasses, position shop towels to help catch excess fuel. Place your index finger and thumb on the retaining clips, push together the fuel line connection then squeeze clips inward. In a gentle twisting motion pull the connection apart. Remember to be ready for any residual pressure in the line to spray out. After the removal of the line, pry the remaining insert off the hard lines. Reinstall into the OEM fuel line for safekeeping.

9. Lay the PRL flex fuel kit out on a clean work surface and familiarize yourself with the connectors.

This is the assembled kit.
This is the male secondary o2 plug.
This is the ground eyelet.
This is the male ECT2 Plug

10. Locate the OEM fuel line bracket removed in step 6.

  • Pull the steel spacers out of the rubber isolators.
  • Peel the rubber isolators out of the OEM bracket
  • Press isolators into the PRL Flex Fuel bracket.
  • Install the steel spacers into the rubber isolators with the washer face facing forward.

11. Remove the short inlet hose from the ethanol content sensor. Keep track of what side you removed. The hose has two different sized fittings on it so direction is key. The fitting side that goes onto the ethanol content sensor has an inner diameter of 3/8”.

12. Install assembly into the factory fuel line bracket mounting location using the OEM hardware.

13. Install the fuel inlet hose that you uninstalled in step 11 onto the OEM feed line and ethanol content sensor.

 14. Route the fuel line through the factory clips you unhooked in step 4, clip the line onto the inlet of the high pressure fuel pump.

15. Remove the inlet hose to gain access to the secondary o2 connectors. Please refer to our other installations for this step. Our car has the PRL High Volume Intake System installed, so it was as simple as using a flat-blade screwdriver to loosen (4) hose clamps and pull the silicone up and out of the car.

16. Route the PRL harness along the intake manifold, following the fuel line, at the area of the high pressure fuel pump, route the harness along the factory wiring harness shown in the pictures, having the o2 plugs terminate near the OEM ones. Place zip-ties around the harness at your discretion, leaving them loose until the rest of the harness is installed.

17. Unhook the rear o2 from the factory bracket. Reaching behind it you have to depress the tab at the bottom of connector and slide it down off of the bracket. Disconnect the OEM rear o2 from the chassis harness.

18. Unbolt the 10mm bolt pictured below and clean ground surface with emery cloth or Scotch-Brite if corroded. Bolt the PRL harness ground eyelet to the block as shown.

19. Plug in the female side of the PRL harness into the factory rear o2 plug.  Clip this portion back into the factory steel bracket.

20. Plug in the male side of the PRL harness into the female chassis harness o2 connector.

21. Route the ECT2 plug down along the rear o2 harness and radiator hose.

22. Locate and remove the ECT plug at the bottom of radiator on the driver’s side. Usually it is possible to do this from above, reaching down along the radiator. If you find this method troublesome, you will have to jack the car up and remove the under tray to gain access to this plug. Please use safe operating procedures and place jack stands appropriately before climbing under the car.

23.Using the remaining zip-ties please fasten the harness down to remain clear of the radiator fan and any other hazards in the engine bay.

24. Reinstall the safety clips at this time and check all connections.

25. If necessary place the car back on the ground. Reinstall intake silicone.

26. Replace 20 amp fuel pump fuse. (Upon first startup, the car may need to crank for an extended time to refill the fuel line.)

27. Last step is to change your Hondata (or KTuner once supported) calibration to enable flex fuel trims!

6 thoughts on “PRL Motorsports 2017+ Honda Civic Type-R FK8 Plug ‘N Play Flex Fuel Kit Install Guide”

  1. does it need anything to plug/cap the factory ECT2 sensor at the bottom of the radiator?
    does it mean the ECU will not get ECT2 signal, which wont matter for engine operation?
    after installing this kit, what setting need to be changed in the Hondata map? like enabling/disabling features/map etc?

    1. There is no need to cap the ECT2 sensor.

      Yes, the ECU will no longer reference ECT2, as this is to be disabled via a checkbox on KTuner/Hondata. This will not matter for engine operation.

      Please see the install guide on our product listing.

  2. why does the Flexfuel kit for FK8 use a rubber hose between the ethanol content sensor and factory fuel line, but the kit for other civic use a hardline? can I upgrade from the rubber hose to the hardline?

  3. My flex fuel kit Gates Barricade fuel line ruptured for no reason…I’m trying to buy the hose but not sure of the part number or dimensions of the hose to replace…any help is appreciated…anyone

Leave a Reply

Your email address will not be published. Required fields are marked *

By submitting this form, you are consenting to receive marketing emails from: PRL Motorsports, 1400 Randall Ct, Export, PA, 15632, http://www.prlmotorsports.com. You can revoke your consent to receive emails at any time by using the SafeUnsubscribe® link, found at the bottom of every email. Emails are serviced by Constant Contact