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MegaSquirt® experimental electronic fuel injection controllers are intended for educational and research use on off-highway or non-pollution controlled vehicles only. They are not intended as a replacement controller for any emissions controlled vehicle that will ever be operated on public roads.

No Tampering

WARNING: In the U.S.A. or Canada, federal law makes it illegal for ANYONE to tamper with, disconnect, remove or otherwise render inoperative ANY automotive emissions related control device. In general, the entire fuel system and all its individual components (including the EFI ECU) are considered 'emissions related control devices'. The penalties for tampering can be substantial. A violation may make you liable for a fine of $2,500 or even more!

"Tampering" means replacing or disabling any emissions related components (i.e. any components that would, or could, affect any vehicle emissions) with an unapproved replacement part. It originally applied primarily to 'professional mechanics' operating from licensed repair facilities.

Revisions to the U.S. Clean Air Act in 1990 (40 CFR Title 2, Part A, Section 203) further broadened the definition of emissions tampering to include virtually ANY type of engine or exhaust system modification, performed by anyone, that alters, or might alter, what comes out the tail pipe. That means any nonstock aftermarket part that is installed on your engine must be EPA-approved and emissions legal (except on the exempt vehicles noted below) if you will be driving on public roads. Canadian federal clean air laws are very similar.

However, federal anti-tampering law does not apply to race cars that are not operated on the street, other full-time off-road vehicles, show cars that are not street driven, or vehicles not factory equipped with emission controls (most 1967 and earlier vehicles). So that exempts all antique cars, and many classic cars and muscle cars.

Aftermarket parts manufacturers who make non-stock performance parts for engines, such as the fuel, ignition or exhaust systems must apply for special certification (an "exemption order" - E.O.) for any parts they want to sell as being emissions legal. The California Air Resources Board (CARB) has been the leading American government body in this respect, so most submit their proposals to CARB to obtain exemptions. Any non-OEM electronic fuel injection controller (such as MegaSquirt®) would be an unapproved replacement part unless it has been granted an exemption.

MegaSquirt® EFI controllers DO NOT have exemption orders in any jurisdiction, and thus are NOT emissions legal for any on-road application of pollution controlled vehicles anywhere in North America (nor any other jurisdiction that has similar legal requirements).

Similar regulations have been, or soon will be, enacted in other parts of the world, including Europe, Japan, and other regions. Check the laws in your jurisdiction to determine if using a MegaSquirt® EFI controller is legal for your application.


Tampering with a vehicle's emission components makes you liable for a federal fine. In addition, if you live in (or move to) a region that has, or may have in the future, an automobile emissions testing program, you may have difficulty registering, selling, or trading-in any vehicle that has been tampered. Depending on the degree of tampering, a vehicle can fail any visual emission testing inspection (even if the vehicle meets the tail pipe emissions specifications) and the owner can incur potentially high repair costs in order to pass inspection (generally returning the vehicle's emission components to 'as new' condition). In most such programs, vehicles are usually required to pass inspection before they are registered (though there may be waivers granted, these often won't apply to deliberately tampered vehicles).

However, the best reason not to tamper with your vehicle's emission control systems is to prevent adding additional pollution to the air. Well maintained vehicles that are kept in their original configuration emit a small amount of regulated pollutants. Tampered vehicles can emit well over 100 times the designed amount. When your vehicle is polluting as little as possible, we can all breathe a little easier. Click here for more information on emissions from automotive engines, and the smog that results.

MegaSquirt® and MicroSquirt® controllers are experimental devices intended for educational purposes.
MegaSquirt® and MicroSquirt® controllers are not for sale or use on pollution controlled vehicles. Check the laws that apply in your locality to determine if using a MegaSquirt® or MicroSquirt® controller is legal for your application.
©2004, 2008 Bruce Bowling and Al Grippo. All rights reserved. MegaSquirt® and MicroSquirt® are registered trademarks. This document is solely for the support of MegaSquirt® boards from Bowling and Grippo.