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wickedstangs
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Fordmuscle.comMIL Eliminators
We won't get into the legal disclaimers here regarding off-road pipes, you know the laws in your state so do as you see fit. We will mention however that removing the catalytic converters will trigger a "check engine" light on 1996 and up Mustangs. This is because the EEC-V engine management system utilizes oxygen sensors both before and after the catalytic converters. The computer expects to see voltage from the aft O2 sensors corresponding to a lean mixture as a result of exhaust gas cleaning by the converters. Removing the converters sends the wrong signal, triggering a check engine light. Fortunately there is a way to eliminate the problem. Several companies sell "MIL Eliminators" (Malfunction Indicator Light). The MIL eliminator is simply a resistor and capacitor circuit placed in the O2 sensor harness that sends the computer the lean signal (300mV) it expects to see.