Air Flow Sensor(MAFS) is digital sensor. Measuring mass of air flow, signal is outputted as frequency(Hz).
ECM performs EGR system feed back control with the information of measured mass air flow. (The role of AFS in diesel engine is different from gasoline engine. Fuel injection quantity is decided by AFS signal in gasoline engine.)
When EGR gas(contains no oxygen) flowing into combustion chamber increases, the air passing through AFS(contains oxygen) decreases. Thus, with the output signal change of AFS 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.
Item
Detecting Condition
Possible Cause
DTC Strategy
? Voltage monitoring
? MAFS circuit
? MAFS component
Enable Conditions
? Engine running
Threshold Value
? Short to battery in MAFS circuit
Diagnostic Time
? 1.0 sec.
Fail Safe
Fuel Cut
NO
EGR Off
YES
Fuel Limit
Check Lamp
Intake air quantity (Kg/h)
Output frequency ( KHz )
Deviation [ % ]
20?
80?
± 3
8
1.97
± 2
10
2.01
40
2.50
105
3.20
220
4.30
480
7.80
560
9.50
Signal frequency increases as RPM rises.