Manufacturers Issue Tamper-Resistance Compliance Guidelines

OPEI urges affected carburetor and engine manufacturers and importers to closely review and promptly adopt suggested best practices in the OPEI Guidance.

The Outdoor Power Equipment Institute (OPEI) has issued a new Guidance Document outlining best practices and guidelines on tamper-resistance compliance for small engines and lawn and garden products.

Over the past year, the U.S. Environmental Protection Agency (EPA) initiated enforcement actions that led to the seizure of small engines and lawn and garden products because of concerns that the engines were equipped with carburetors that could be illegally adjusted by repair facilities and consumers. Such illegal tampering could potentially cause emissions in excess of the engine’s EPA-certified configuration. In these cases, EPA determined that the carburetors were equipped with inadequate “tamper-resistant” features. 

To prevent such illegal tampering and adjustments, carburetors typically have limiter caps or seals that prevent adjustments outside of the certified configuration. In some products, adjustments can only be made using “special tools” exclusively supplied by a manufacturer to their repair networks and dealers. Under the pre-existing regulatory framework, EPA Enforcement re-tested engines and carburetors to determine whether the carburetors had effective “tamper-resistant” features.

To improve the current process, OPEI has issued an influential Guidance Document on Tamper-Resistance Compliance. “OPEI urges all the affected carburetor and engine manufacturers and importers to closely review and promptly adopt the suggested best practices in the OPEI Guidance,” said Kris Kiser, president and CEO of OPEI. 

The OPEI Guidance recommends the following:

  • Carburetor or engine manufacturers should first obtain pre-approval by the California Air Resources Board (CARB), which tests each carburetor to ensure that its “tamper-resistant” mechanisms are compliant.
  • The CARB pre-approval—along with detailed descriptions and pictures of the tamper-resistant mechanism or device and the manufacturer’s “special tools” —should be submitted electronically to the U.S. EPA Certification Office, as part of the engine certification applications for the upcoming 2012 and subsequent model year engines.

“As long as this documentation is submitted to EPA and the tamper-resistant mechanisms have been produced and installed as approved by CARB, then manufacturers should be able to manufacture and/or import engines and products without market disruption,” said Bill Guerry, OPEI counsel. 

In those exceptional circumstances where CARB has not tested or approved the carburetor, manufacturers should submit documentation to EPA on their own tamper-resistant testing results (pursuant to the OPEI Guidance) demonstrating satisfactory tamper resistance. 

OPEI expects EPA to issue its own enforcement alert and certification guidance this fall that will provide clarifications that are similar to the OPEI Guidance Document. To obtain a copy of the OPEI Guidance, go to