DIESEL CONTROL SYSTEM
DTC P0101 MASS OR VOLUME AIR FLOW CIRCUIT
MAFS & IATS
Air Flow Sensor(MAFS) is digital sensor. Measuring mass of air flow, signal is outputted as frequency(Hz). ECM per-
forms EGR system feed back control with the information of measured mass air flow. (The role of MAFS in diesel engine is
different from gasoline engine. Fuel injection quantity is decided by MAFS signal in gasoline engine.)When EGR gas(con-
tains no oxygen) flowing into combustion chamber increases, the air passing through AFS(contains oxygen) decreases.
Thus, with the output signal change of MAFS accompanied by EGR actuator actuation, ECM determines the amount of
recirculated EGR gas quantity.
NOx is produced from the reaction of nitrogen and oxygen.
If least intake air required for complete combustion flows into combustion chamber by controlling EGR gas(contains
no oxygen) which is recirculated to combustion chamber, NOx decreases because there is no supplementary oxygen
to react with nitrogen.
P0101 is set when MAFS output voltage above 4.8V is detected for more than 1.0 sec.. This code is due to short to battery
in signal circuit or open in ground circuit.