A20D05 Mercedes Fault Code :
Read the description of A20D05 in ACM21T and the engine lights up for ACM21T Aftertreatment Control Module code, there are some possible causes for it.
Component 17V01: Exhaust aftertreatment run-on check diode has an open circuit.Component 17V01: Exhaust aftertreatment run-on check diode is incorrectly connected.