Subaru NexGen Flex Fuel

8/28/2023 – Update!

2008-2014 Subaru STI NexGen Flex Fuel Support

Today, we’re excited to announce NexGen Flex Fuel support for 2008-2014 STIs.  The existing NexGen Flex Fuel hardware previously made available for 2015-2021 STIs is now listed as compatible with USDM 2008-2014 STIs.  An all new NexGen Stage 2 + Flex Fuel Power Package along with “upgrade” power packages are also available for the GR/GV STI.  To support these new packages, we have also developed and are offering a host of Off The Shelf (OTS) Maps, available for download from the COBB website.

COBB NexGen Stage 2 + Flex Fuel Stage Power Packages and Off The Shelf Maps have undergone and passed third party emissions / reasonable basis testing and are currently available in 49 states as we continue to seek a CARB EO.

NexGen Stage 2 + Flex Fuel Power Package


A new NexGen Stage 2 + Flex Fuel Power Package is now available for 2008-2014 STIs.  At the core of this package is our 50-State Legal NexGen Stage 2 Power Package.  The airflow and fuel system upgrades in that package in addition to the NexGen Flex Fuel hardware are required in order to take advantage of our SEMA Certified NexGen Stage 2 + Flex Fuel Off The Shelf (OTS) Map.

Stage 1 to NexGen Stage 2 + Flex Fuel Power Package Upgrade

Stage 1+ to NexGen Stage2 + Flex Fuel Power Package Upgrade

For customers who may already have an Accessport or Accessport and Intake, they can choose one of our “upgrade” power packages, which include all of the fuel system upgrades, turbo inlet hose, spark plugs, and NexGen Flex Fuel components.

Power Gains

Supporting COBB Off The Shelf Maps can be downloaded from the Maps section of our website after configuring your applicable vehicle.  For additional information on COBB OTS Maps, see the Map Notes Page.

  • NexGen Stage2 1050x + Flex 91 v520 HWG.ptm
  • NexGen Stage2 1050x + Flex 91 v520 LWG.ptm
  • NexGen Stage2 1050x + Flex 91 v520.ptm
  • NexGen Stage2 1050x + Flex 93 v520 HWG.ptm
  • NexGen Stage2 1050x + Flex 93 v520 LWG.ptm
  • NexGen Stage2 1050x + Flex 93 v520.ptm
  • NexGen Stage2 1050x + Flex ACN91 v520 HWG.ptm
  • NexGen Stage2 1050x + Flex ACN91 v520 LWG.ptm
  • NexGen Stage2 1050x + Flex ACN91 v520.ptm

Vehicles utilizing the complete NexGen Stage 2 + Flex Fuel power package and accompanying OTS Map can expect to see gains as displayed below.

NexGen Flex Fuel Component Compatibility

The below NexGen Flex Fuel components are now listed as compatible with 2008-2014 STIs.  Additional information for each component is covered in the original release content, found below.

NexGen Flex Fuel Ethanol Sensor Kit


Subaru Fuel Pressure Sensor Kit


NexGen Stage 2 to NexGen Stage 2+ Flex Fuel Package


NexGen Flex Fuel is finally here.  Today we are extremely excited to release the first phase of NexGen Flex Fuel support for our Subaru platform here at COBB, covering USDM 2015-2021 WRX STI.  This release consists of an all new NexGen Flex Fuel Ethanol Content Sensor Kit, Stage Power Packages with supporting Off The Shelf Maps, and support in Accesstuner Pro for custom tuning.  COBB NexGen Stage 2 + Flex Fuel Stage Power Packages and Off The Shelf Maps have undergone and passed third party emissions / reasonable basis testing and are currently available in 49 states as we continue to seek a CARB EO.

The Flex Fuel Kits

Introducing NexGen Stage 2 + Flex Fuel Power Packages!  These power packages are based upon our 50-state legal NexGen Stage 2 Power Packages, simply adding NexGen Flex Fuel into the mix by way of our all new ethanol content sensor kit and fuel pressure sensor kit.  For 2015-2021 STI there are three flavors of the package, the difference being which intake is included.  All three of these Power Packages are supported by COBB Off The Shelf Maps.

NexGen Stage 2 + Flex Fuel Power Package 2015-2018 STI (SF Intake)

NexGen Stage 2 + Flex Fuel Power Package 2019-2021 STI, 2018 STI Type RA (SF Intake)

NexGen Stage 2 + Flex Fuel Redline Carbon Fiber Power Package 2015-2021 STI, 2018 STI Type RA


At the heart of NexGen Flex Fuel is our all new module and harness solution.  This module takes signal from the ethanol content sensor placed in your car’s fuel line and converts it into something that the ECU can then comprehend and utilize to make calibration changes on the fly to account for any change in ethanol concentration.

NexGen Stage 2  to Nexgen Stage 2+ Flex Fuel Upgrade Package

This upgrade package is all that is necessary for those who are already taking advantage of our 50-State Legal NexGen Stage 2 Power Package.  With the supporting fuel system already handled within that package, all that is needed in order utilize our supporting Off The Shelf Map are the two sensor kits below for ethanol content and fuel pressure.


NexGen Flex Fuel Module + Harness Kit

For those who were utilizing our previous Flex Fuel components, this upgrade package is all you would need in order to move into the NexGen product line.  Your existing COBB fuel rails, lines, and ethanol content sensor configuration can be retained.  This kit includes the bare necessities; an all new NexGen module and plug-and-play harness.


Power Package Upgrade Kits

If you are already utilizing a COBB Stage Power Package and want to move into a NexGen Flex Fuel Power Package, we have you covered!  The packages below are available for vehicles that are currently in a Stage 1 or Stage 1+ (intake) configuration.

From current Stage 1 (Accessport re-used)


From current Stage 1 + Intake (Accessport + Intake re-used)


Off The Shelf Maps and Power Gains

These map files are only available to be downloaded from the Maps section of the COBB website.  Download Flex Fuel Off The Shelf Maps HERE.

  • NexGen Stage2 1050x + Flex 91 v510 HWG.ptm
  • NexGen Stage2 1050x + Flex 91 v510 LWG.ptm
  • NexGen Stage2 1050x + Flex 91 v510.ptm
  • NexGen Stage2 1050x + Flex 93 v510 HWG.ptm
  • NexGen Stage2 1050x + Flex 93 v510 LWG.ptm
  • NexGen Stage2 1050x + Flex 93 v510.ptm
  • NexGen Stage2 1050x + Flex ACN91 v510 HWG.ptm
  • NexGen Stage2 1050x + Flex ACN91 v510 LWG.ptm
  • NexGen Stage2 1050x + Flex ACN91 v510.ptm

This dyno graph shows the ranges of horsepower and torque that you can expect to experience when using the COBB NexGen Stage 2 + Flex Fuel Power Package and accompanying OTS map. Using 93 octane with up to E10, our development car made a peak of 307 whp and 338 wtq., exactly what you’d expect to make on a normal NexGen Stage 2 Power Package. Then, without changing a single part on the car and using the exact same tune, we bumped the ethanol percentage in the tank up to E65 where the car made a peak of 332whp and 373wtq.  With a full tank of E85, we topped out at 336whp and 379wtq!  As you can see, the majority of the gain occurred by simply getting the car to that E65-ish range and the extra 20 points of ethanol content did not produce an overwhelming difference in power.

Looking for more specifics about our Off The Shelf Maps? Head over to the Map Notes Pages linked below.


These map files are only available to be downloaded from the Maps section of the COBB website.  Download Flex Fuel Off The Shelf Maps HERE.

Custom Tuning Support

Subaru Accesstuner Pro HL has also been updated to support NexGen Flex Fuel hardware.  COBB Protuners can create custom calibrations for emissions compliant vehicles that are utilizing our NexGen Flex Fuel Ethanol Sensor Kit and 5-pin Fuel Pressure Sensor Kit.

Find your preferred COBB Protuner HERE.

126 responses to “Subaru NexGen Flex Fuel”

  1. This new flex fuel kit you have coming out…are there going to be any adapters for the old flex fuel kit so we can use. Or is this a total different setup? You guys said that since the old flex fuel kit plugged into the TGV is why it was not emission compliant, correct?

    Also, are you guys making any redline carbon fiber intakes for the 2008-2014 STIs?

    • While the overall operation is different, we will have an offering that will allow those with our old Flex Fuel kits to upgrade their configuration to the NexGen solution.

      We are not currently working on a Redline intake for 2008-2014 STIs, but it is something we would like to do at some point.


    • The initial release is for 2015-2021 STI (EJ), we plan to add support for more vehicles through the end of the year.


    • Flex Fuel allows you to have a single calibration that is compatible with any blend of gasoline-ethanol. In an engine’s operation of “suck-squeeze-bang-blow”, a higher ethanol content makes it possible to increase the size of the bang without detrimental results.


    • We will not be offering a buy-back or “trade-in” program however we will have a lower-cost option available for those who do not need to change their entire configuration in order to use the new solution.


    • We are not going to be offering pre-orders but will have plenty of product on hand for release day!


    • Not initially, but we do hope to support the same vehicles with NexGen as we did with the initial flex fuel solution.


    • We will have an option for those who have the old flex fuel kit to upgrade to our NexGen solution.


  2. I need a new turbo upgrade and rub flex fuel on my 2016 STI. When will the new kit be available? ETA?

    • Initial launch will be for 2015-2021 STI. Additional vehicle support will be added throughout the rest of 2023.


  3. Will it be available for the 15-21 wrx FA platform?
    I been wanting to go e85 with my 17 wrx but EPA hit Cobb a week after I got it.

    • Hey Zack, we are working on re-adding Flex Fuel to the FA WRX but it will not be a part of this initial NexGen release.


  4. Will existing Accesstuner Race customers have access to “Subaru nexgen flex fuel” features?

    Will differential fuel pressure compensation be migrated to a “nexgen” implementation?

  5. My understanding is these NexGen F.F Kits will obviously be CARB EO approved.

    So my question is, what makes the kit?
    Im thinking, in order to properly run F.F at a stage 1-2 level, the kit would need:
    – Down pipe
    – Injectors (1000s?)
    – Fuel pump
    – F.F Hardware
    – MAF and MAP
    – Intake (as an option for those running stage 1 CAN)

    I have a 2011 WRX, and i reverted back to stock after running E85 for years, just to meet CARB requirements. So I, and presumably many like me, will need all these parts once again. So im hoping “the kit” is all inclusive.

    • Hey there! This initial release will be what we call a “49-State” release as we do not yet have an EO from CARB. While we have completed and passed third party emissions testing, we have not yet received an EO from CARB. As far as the kit for your 2011 WRX goes, it is currently TBD. Our focus thus far has been on 2008-2021 STI since we do already have a NexGen Stage 2 Power Package to support the fueling requirements, we plan to develop a similar package for GR WRXs in the near future.


    • If you’re paying attention to our website or social channels we will definitely make it known when the NexGen Flex Fuel components are available for purchase. Alternatively, signing up for our Subaru mailing list by entering your information HERE will ensure you receive an email from us as well.


    • The new power package will be supported by an accompanying OTS Map that has gone through and passed third party emissions testing. We are still working towards EO coverage through CARB.


  6. So those with the old flex fuel kit will be able to trade for the Next Gen flex fuel kit only if you bought directly from Cobb?

    • While we initially planned to offer a trade-in program, we have opted to go a different direction to make things easier for existing customers. Instead of having to purchase the full kit up front for full price and then wait for a credit after shipping your old hardware back, we are just going to sell a lower priced “upgrade package” which only includes the components you would need (module + harness) to upgrade to the NexGen configuration.


  7. Hey Marshall!
    Just saw the good news on the new FF kits for 2015+!
    What’s the word on the option for 2008 – 2014 without the older kits already in hand?

  8. anyone is going to explain how it works without disabling the CEL. if it still plugs into the TGV or how it works and where it plugs in. Previously CEL needed to be disabled because the ethanol sensor was sending signal over the TGV valve position sensor signal line, how is it all going to work now and how is the signal going to be sent to the ECU/ accessport?

    • The NexGen kits are still injecting data through the TGV Sensor connector but have come up with a proprietary method for that single 0-5v input to transmit data for multiple inputs (Ethanol Content, Fuel Pressure, and TGV Sensor location).


  9. Hey Marshall, when will the upgrade kits be available and will old tunes still work with the upgrade kit

    • We hope to offer the same vehicle support we had before with the NexGen kits, TBD on timeline though.


  10. What is the time frame on getting that carb eo number approved? As this would be awesome in leaving my vehicle as is.

    • We, unfortunately, don’t really have visibility into the timeline once an application is made to CARB. It’s an all new process, so it could be a bit.


  11. I purchased the old flex kit last year before the update and never got to install or use it, for my 2019 wrx, hoping it won’t just be a paperweight and I can use it or exchange it for when the new one comes out

    • Hey Chris, our offering for the 2015-2021 WRX would likely follow a similar strategy to what is currently available for the STIs. That is, a full kit along with the ability to change only the necessary parts to use the new solution. It is most likely that the only reusable part will be the Ethanol Content Sensor and any connecting fuel lines. The wiring harness/module you have will not be compatible. I’ll have our CSR team reach out and explain your options if you’d like.


  12. I have a 2018 WRX with the stage 2 NexGen package, will there be a CARB approved flex fuel kit available for purchase? And if so what will the timeframe be? Thanks.

    • Hey there! We, unfortunately, do not have an ETA for receiving an EO from CARB for NexGen Flex Fuel.


  13. Will this be available for the 2022 WRX?? I’ve heard the fuel pumps can handle full E85 and I can’t wait to try it

    • Not available yet, but we certainly intend to added when able! Some preliminary testing does show that the pump can handle higher ethanol contents, we’ll see how long term durability testing shakes out.


  14. with the 2018 sti I have the cobb gesi downpipe installed and an intake that is not installed If get the SUBARU STAGE 1+ TO NEXGEN STAGE 2 + FLEX FUEL POWER PACKAGE UPGRADE STI 2015-2021, will I have to put the stock downpipe back on, or can it be tuned with the intake and cobb downpipe?

    • Hey RJ!

      If you wish to use the supporting COBB Off The Shelf Map for NexGen Flex Fuel you will indeed need to revert to your stock downpipe.


  15. Please help, I’m confused. I’d thought it was illegal in California because it’s illegal to have a non OEM tune, or run flexfuel on a car that doesn’t have an option for flexfuel as an OEM.

    • Hey MJ,

      We do not yet have a CARB EO for the flex fuel components or calibration, so they are not available for use in California. Our NexGen Stage 2 Power Packages do have coverage by CARB EOs and are available in California, more information on them here :


    • Hey Brenden,

      We are hard at work on kits for 2008-2014 STI and should have some news soon!


    • TBD. We’re working on developing the Power Package (fuel system upgrades) to support flex fuel on that platform, should have a better idea of timeline by the end of the year.


  16. Hey I have a question.
    Is inexgen available to be purchase in LA CA? Or by when will it be available?
    I have a Subaru wrx sti limited 2020.
    Thank you (:

    • Hey Randy,

      While our NexGen Flex Fuel solution has undergone (and passed) third party emissions testing, it is not currently covered by a CARB EO, so it is not available in California. We are working with CARB on a path to 50-state coverage and hope to achieve that in the future.


  17. For a stock ’17 WRX do I need the power package or do I just need a different fuel pump + access port + flex fuel kit?

    Since there are off the shelf maps, do I still need a protune/etune once I have the kit?

    • Hey Chad,

      We do not yet offer our updated version of Flex Fuel for the 2015-2021 WRXs. Once available, all you will need is the flex fuel hardware and an Accessport as an Off The Shelf Map will be included.


  18. Sounds like the Flex Fuel kit for the 2015-2021 WRX is in the works and will be out soon.

    Assuming there will be nexgen staged power packages, would you consider make a staged power package that is just the flex-fuel kit + EBCS + HPFP with an OTS map that is CARB compliant?

    Sounds like this would be a best bang for the buck kit with a lower $ entry point.

    • Hey Kishan,

      We are indeed pretty well into flex fuel development for 2015-2021 WRX and are definitely aiming to offer multiple packages and OTS Maps for those cars.


  19. When the 08-14 WRX version comes out I’m assuming it will be compatible with LGT/OBXT as well, correct?

    • Still a TBD on NexGen for GD applications. We’d love to offer the same vehicle coverage of our initial flex fuel product line, but new hurdles have made releasing these products increasingly more difficult, time consuming, and expensive.


    • Hey Tyler! Flex Fuel for the VA WRX has been a project we’ve been working on. We don’t have an exact ETA when we will have a final released product, but it should one be of the next projects to be available. You can always subscribe to our emails to be updated once we have new news for you!

    • We know. 🙁

      The development work for Mk7 GTI / R Flex Fuel is complete and ready to release, we are simply awaiting passing emissions data of our calibration and hardware before we can make it available.


  20. What is the VA wrx eta for the next gen flex fuel kit? I read in earlier replies later this year. is it looking like early next year?

    • Hey there! We were initially targeting a late 2023 release timeframe. That has shifted to very early 2024, likely mid-late January.


  21. I always come back to this page to see if there’s any new news in the comments for the GR/GV! (08-14 WRXs) Anything you can share about NextGen Flex Fuel for those non-STI models?

    • Hey Kyle! We’re in the midst of developing our NexGen Stage 2 Power Package for the GR/GV WRXs and are hoping to have some positive news on that towards the end of the year or early 2024. Once we have displayed emissions compliance on the supporting NexGen Stage 2 package, we can add in our Flex Fuel components and move into emissions testing on ethanol. Still a little early to provide an ETA, but I’d hope sometime in the Spring of 2024 we are able to release Flex Fuel for those cars.


  22. Why is a further back generation platform getting priority over the VA for flex fuel? This makes no sense, just go in order.

    • We do not have a solid timeline on a release date but are actively working on adding support for GR/GV WRX. Once we have an emissions compliant package that is able to support flex fuel (fuel system upgrades) we will be able to move forward with emissions testing on a flex fuel package and map. We are hoping to be able to do that in the early part of 2024.


    • We are hoping to bring Flex Fuel back for 2015-2021 WRXs in early 2024. Our goal is to have the new flex fuel hardware and calibrations emissions tested in January and make product available right around the end of January/early February.


  23. Still waiting for 04-07 STi Next Gen Flex fuel. Do you think it will be available in 2024 or are you just going to forget about us?

    • It’s possible we may get to those cars later in 2024, but that is not a project that is currently being worked on.


  24. Is a late January to early February release date still happening for the 15-21 WRX flex fuel packages?? Eagerly awaiting!

    • Flex Fuel for VA WRXs is going to look a bit different than our NexGen kits for EJ powered cars. We are currently working through emissions testing and are hoping to release them in the next month or so. For now, here’s a quick article that gives some insight into what the VA kits may look like :


  25. Is there a way I can pre-order the flex fuel kit for FA 2016 wrx? That’s the cherry on top and I have all of my aftermarket parts sitting on the floor to save money from pro tuning twice

    • Not likely as we are still working through some unexpected emissions results with our testing partners. Luckily, the parts are on the shelf and ready to ship and the software side of things will be ready to roll in just a few days. As soon as we have positive news out of emissions testing, it’s game-on!


    • Nothing worth noting quite yet. We are hoping to be back in the emissions lab the week of March 18th and will be eager to see results from that session.


  26. Hey Marshall, given your previous comments about emissions testing on 15-21 wrx. Will the new flex fuel kits + maps be CARB approved? And how many maps are being put up for approval? In terms of mod options. Is there a flex fuel + 3 port ebcs map or will we have to do specific mods to be able to run the one approved FF map for example. Any insight here would be helpful. And if possible an update on flex fuel please. As there are tons of us checking this page every day haha.

  27. It’s almost April now, any specific updates on the GR/GV WRX package? Anything we could help with? My tuner is getting weary of waiting, don’t let him lose hope!

  28. My 2021 FA20 is wondering when the flex fuel kit is releasing. I know you guys are working on it but wondering if there’s a date on it. Thanks!!

    • At this point we are at the mercy of emissions testing. Things are progressing well and results are looking good, we are ready to release as soon as testing is completed!


  29. Do we have any idea of when testing is going to be complete?? We’ve been waiting a while. ‘15 WRX here

    • We are hoping to hear back with results on pump gas by the end of this week (April 19th).


  30. Thank you for all of the updates, Marshall! Been reading through all of the comments regarding the FA20 kit and it sounds like progress is being made. I know we are all happy to hear it and looking forward to the release.

    Hopefully testing went well this past month! Anything new to share?

    • We have passed emissions testing and at this point are just waiting on official documentation from the emissions lab. Anticipating a release mid-May.


  31. Hi Marshall, how far off before the GD nexgen is being worked on? Any chance we will be included in the next year or so?

  32. Any updates on the GH WRX upgrade package? My IAG 500 is sitting at half its power capacity, just waiting for your kit! Thank you for your efforts!

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