Intake Air Temperature Sensor (IATS) is NTC thermister which voltage gets low if the temperature comes to be high. Installed inside of both MAFS and BPS, it senses intake air temperature. In case of EURO-4 diesel engine, IATS is installed in front of turbocharger (inside of MAFS) and behind it (inside of BPS). Comparing air temperature from both sensors (one is intake air temperature, the other is air temperature passing through turbo charger), more accurate sensing of intake air temperature is possible. With intake air temperature signal, ECM performs EGR control correction and fuel injection quantity correction. (MAFS is needed for EGR FEED BACK control in electronically controlled diesel engine. The calculation of air density at certain temperature is required to perform EGR FEED BACK control correctly.)
In case of replacing MAFS, perform the "COMPONENT CHANGE ROUTINE" procedure with GDS. If the "COMPONENT CHANGE ROUTINE" procedure has not completed until automatic learning completed, it may cause vehicle performance and exhaust gas problem.
P0112 is set when the voltage below 73mV - minimum output voltage of IATS (inside of MAFS) - is detected for more than 1 sec. This code is due to short to ground in IATS signal circuit.
Item | Detecting Condition | Possible Cause | ||
DTC Strategy |
•
Voltage Monitoring |
•
IATS #1 circuit
•
IATS #1 | ||
Enable Conditions |
•
IG key ON | |||
Threshold Value |
•
When output signal is below the minimum value (below 73mV). - Short to ground in signal circuit. | |||
Diagnostic Time |
•
1 sec. | |||
Fail Safe | Fuel cut | NO |
•
Fixed at 50℃ | |
EGR Off | NO | |||
Fuel Limit | NO | |||
Check Lamp | OFF | |||
Temp. | Resistance |
0℃ | 5.11 ~ 5.90 ㏀ |
20℃ | 2.29 ~ 2.56 ㏀ |
40℃ | 1.09 ~ 1.24 ㏀ |
60℃ | 0.56 ~ 0.66 ㏀ |
Fig. 1) Signal waveform of MAFS at idle.
Fig. 2) Signal waveform of MAFS at 3000rpm.
☞ The higher engine rpm, the higher output frequency.
Fig. 3) Reference signal waveform which is outputted in of 'ATS signal' terminal 'AIR FLOW SENSOR'.
