Wide Band EFIEs

These devices are used for wide band sensors. They should be used on all 5-wire and 4-wire wide band oxygen sensors. Wide band sensors are sometimes called AFR (Air/Fuel Ratio) sensors.  The packages in this section include narrow band EFIEs for use on the downstream sensors.  So far, all vehicles we have encountered, that use wide band sensors, only use them upstream of the catalytic converter.  Narrow band sensors are used downstream.  We strongly recommend treating all of your sensors for best results.