The SM-AFR Gen4 is a tuner grade Bosch LSU 4.9 wideband oxygen sensor controller with digital/analog outputs for 3rd interface. Accurately reads the air/fuel ratio of any internal combustion from 0.68 Lambda to 1.36 Lambda (10:1 - 20:1 AFR *Gasoline). Fully plug and play, no sensor calibration is required. Compatible with Gasoline, Diesel, Ethanol, Methanol, E85, LPG, CNG. Accurate to 0.1AFR with less than 100mS reaction time from rail to rail. Advanced sensor health monitoring, displays oxygen sensor health and reaction time when connected to DM-6 gauge.