What is a reductant heater a control performance?
What is a reductant heater a control performance? The reductant heater control system is used by the Powertrain Control Module (PCM) to heat up the Diesel Exhaust Fluid (DEF) to prevent it from freezing. Diesel exhaust fluid is sprayed inside the catalytic converter to reduce NOx emissions. What does p20b9 mean on a reductant heater? A stored code P20B9 means that the powertrain control module (PCM) has detected no voltage in the control circuit for the on-board reductant heater designated with the letter A. This designation is used where multiple reductant heaters are in use, consult a vehicle specific repair...