The attached Manufacturers Advisory Correspondence (MAC) provides the Air Resources Board (ARB)'s guidance for either the engine manufacturer or the diesel injection pump manufacturer to obtain ARB's approval of the tamper-resistance methods before ARB certifies such engines. The engine manufacturer alone must obtain approval of all other tamper-resistance methods for engine-based emission-related adjustable parameters, such as the turbocharger wastegate adjustment, or the speed adjustment on constant-speed engines.
