AEM Fail Safe Wideband
- The AEM Failsafe Device is a wideband o2 meter that not only displays Air Fuel Ratio, but can also be programmed with user-defined limits, that can activate an output when exceeded. What does this mean? You can set the parameters for the wideband to say "if the air fuel ratio goes leaner than 13:1 while the car is making more than 6psi of boost, activate the output wire". It's up to you to wire the output wire to accomplish the "failsafe" action you see fit. For example you could cut ignition, or cut the power to the injectors, when the AFR parameters are exceeded. Or you could have the output wire trigger a relay that turns your boost controller off (returning the system back to wastegate-spring boost) when it encounters a problem. All of these things can save your engine from breaking in the event that there is a problem.