Component description Turbo air and coolant temperature sensors Turbo air B197 (51.27421–0165) Characteristic R=f (- н ) 2 3 4 1 Plug connection Coolant B124 (51.27421–0172) Characteristic R=f (- н ) 2 4 1 3 Plug connection Function The turbo air and coolant temperature sensors are NTC resistors. The coolant temperature sensor is lo- cated in the coolant circuit and the turbo air temperature sensor in the turbo air circuit after the intercooler. They supply the control unit with information relating to the coolant and turbo air temperature. 17