Subaru Flex Fuel Ethanol Sensor Kit - WRX 2015-2019

$ 600.00

Availability: Ships in 24 hours
Product Code: 324600

California Residents: Prop 65 Warning

Free Shipping


A complete plug and play solution enabling users to convert their supported Subaru WRX to a Flex Fuel configuration without losing factory compensations. This is the easiest to use and most sophisticated Flex Fuel kit on the market. Utilizing OEM fuel and electronic connectors, the Ethanol Sensor Kit measures the ethanol content of fuel being fed to the motor. That data is then converted into a signal that the ECU can use for adjusting calibrations and to be displayed on a custom Accessport monitor.

Fuel System Considerations

As with other DIT platforms i.e. VW, BMW, Mazda, the fuel pumps in Subaru DIT vehicles are not designed for ethanol use beyond 10-15%. That said, ethanol levels between 15-30% are generally well tolerated. Those comfortable with mild risk can run ~E30 and enjoy improved knock resistance, charge air cooling, and a mild improvement in engine power potential. While you can't get E30 at the pump, pumping a combination of E0/E10 gas and E85 in an appropriate ratio will allow blending of a near E30 mixture in your tank.

On DIT platforms not set up for flex fuel from the factory, at greater than 30% concentration, ethanol has caused oscillating fuel pressure first, progressing to loss of fuel pressure, high pressure fuel pump damage, even making the vehicle inoperable in some cases. Sudden loss of fuel pressure can cause sudden loss of acceleration, stalling, which can reduce braking performance and steering control. Long story short, while the power potential is very attractive, use of high ethanol content fuel is at your own risk.

COBB has performed internal testing in multiple geographic locations with different fuel sources in addition to compiling data from COBB retail shops, our Protuner network, and customers. Results varied significantly. Some users ran several tanks of E85 in a row without issue while some experienced serious loss of fuel pressure in as little as 1-2 tanks of fuel.

We suggest monitoring fuel pressure for oscillations. After having fuel pressure issues, some users were able to flush the HPFP (high pressure fuel pump) out with low ethanol gasoline and get it to operate normally again, while others had to replace the whole pump assembly before they could safely drive the car again. After replacing the pump some users experienced repeat failures if they continued to run E85 fuel.

Requires custom tuning. CLICK HERE to find nearest COBB Shop or Protuner for a custom Flex Fuel tune.


The Flex Fuel Ethanol Sensor Kit is a requirement for converting your supported Subaru to a Flex Fuel configuration. The Ethanol Sensor Kit measures the ethanol content of fuel being fed into the motor and converts it into data that can be utilized by the car's ECU.

Subaru Flex Fuel Ethanol Sensor Kit - WRX 2015-2019
  • Completely Plug and Play Solution
  • Billet Aluminum Converter Case
  • OEM Quality Electrical & Fuel Line Connectors
  • Utilized by COBB Flex Fuel Tables, Retains All Factory Compensations
  • Custom DTC Error Reporting for Water in Fuel

Customer Photos

Subaru Flex Fuel Ethanol Sensor Kit - WRX 2015-2019 is rated 5.0 out of 5 by 6.
Rated 5 out of 5 by from Brazilian GAS You probably don't know, but here in Brazil, we can't find any e0 or e10 fuel, the "purest" gasoline avaiable here is E25, but in a very restrict way, normaly, will will be able only to fill up your tank with the "regular" E27 fuel. Just for intelligence, the WRX's sold here on Brazil, run efficiently with e27 regular fuel, without any mod at all, even knowing our WRX look more the JDM than USDM, I think that is safe to run even with E30 without any mod, and the sensor would be helpful for e50+ fuel... it would be great if we can test it with the E98 avaiable here in Brazil.
Date published: 2017-07-20
Rated 5 out of 5 by from Works great Plug and plays perfect with 2018 wrx. E40 with a good timer pulls hard :)
Date published: 2018-07-08
Rated 5 out of 5 by from Simple install, quality product! Bought this after hearing about the power gains from flex fuel. Phenomenal product, very well put together. Much easier than the delicious tuning kit. It took longer to empty the fuel pressure and remove the battery than it did to install the lines, harness, and sensor. Thanks again Cobb for another great product!
Date published: 2018-06-06
Rated 5 out of 5 by from Easy install. Removed restrictive girl love Easy install. Does what it's supposed to do. E85 ftw
Date published: 2017-11-29
Rated 5 out of 5 by from MUST HAVE!!! Best mod second to the access port. Install was a joke as well. I picked up 70hp on stage 1.
Date published: 2019-04-11
Rated 5 out of 5 by from It is what it is I haven't installed yet but I imagine it does what's design to do.
Date published: 2019-04-12
  • y_2019, m_7, d_15, h_4
  • bvseo_bulk, prod_bvrr, vn_bulk_2.0.12
  • cp_1, bvpage1
  • co_hasreviews, tv_0, tr_6
  • loc_en_US, sid_324600, prod, sort_[SortEntry(order=RELEVANCE, direction=DESCENDING)]
  • clientName_cobb
  • bvseo_sdk, p_sdk,
  • CLOUD, method:getContent, 26.57ms