The People of America's Oil and Natural Gas Indusry

E15 and Check Engine Light Malfunctions

Bob Greco

Bob Greco
Posted January 30, 2013

Earlier this week API highlighted new research by the Coordinating Research Council (CRC) on serious potential problems with vehicle fuel systems when operated on E15 fuel – gasoline containing 15 percent ethanol.

In addition to CRC’s research, we want to call attention to a recent paper from Oak Ridge National Lab (ORNL) that was published by the Society for Automotive Engineers (SAE).  This study examined the effects of E15 on malfunction indicator lights (MIL), also known as “check engine lights.”

As might be expected given the source sponsoring the SAE paper, the study attempts to downplay the risk of a substantial number of MIL illuminations with E15 and with E20.  Nevertheless, two of the main conclusions (from the last page of the paper) are very telling and support the concerns that the auto and oil industries have been conveying all along (emphasis added):

Results show that MIL illumination should increase with ethanol content, but the rates of illumination will vary significantly by vehicle model.  Thus, experience for a given vehicle model may differ quite significantly from a fleet-average estimate of MIL illumination rates.”


“Some vehicle models do not appear to be at significant risk for a substantial number of MIL illuminations with E15 fuel, and a smaller number do not appear to be at significant risk even if E20 is used.  One OEM (original equipment manufacturer) appears to be at higher risk of experiencing a significant number of MIL occurrences with E15 use than other OEMs.

There are a couple of important takeaways from both the CRC and the ORNL research:

  • Not all vehicles are impacted.  Some 2001 and newer vehicles operate on E15 without incident.  But testing by CRC and ORNL has determined that some vehicles do not.
  • Vehicles can have different problems with E15.  One vehicle may have a fuel pump system issue.  A different vehicle might have accelerated valve wear.
  • A few failures can translate to millions of cars.   One or two popular models that have problems can represent millions of vehicles on the road today.  This means a significant number of motorists can be impacted.

The larger point is that with thorough testing – like those conducted by ORNL and CRC – we know that E15 could be responsible for significant problems in vehicles. When EPA green-lighted E15 use, it knew E15 vehicle testing was ongoing but decided not to wait for the results – most likely to raise the permissible concentration level of ethanol in fuels so that greater volumes could be used, as required by the Renewable Fuel Standard (RFS).

EPA should pull back its E15 decision, and the RFS, which drove the premature and irresponsible decision to OK E15’s use, should be repealed.