3.
Is the problem found?
▶ Repair the trouble causing part and go to "Verification of Vehicle Repair".
▶ Go to "Signal Circuit Inspection ".
Intake Air Temperature Sensor(IATS) is NTC thermistor. 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 temperture is required to perform EGR FEED BACK control correctly.)
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 circuit ● IATS component | ||
Enable Conditions | ● IG KEY "ON" | |||
Threshold Value | ● When output signal is below the minimum value ( below 0.073V ) | |||
Diagnostic Time | ● 1 sec. | |||
Fail Safe | Fuel cut | NO | ● Intake air temperature is considered as 20℃ | |
EGR Off | NO | |||
Fuel Limit | NO | |||
Check Lamp | NO | |||
Temperature (℃) | -40 | -20 | 0 | 20 | 40 | 60 | 80 |
Resistance (KΩ) | 35.14 ~43.76 | 12.66 ~15.12 | 5.12 ~5.89 | 2.29 ~2.55 | 1.10 ~1.24 | 0.57 ~0.65 | 0.31 ~0.37 |
Electrical systems consist of a lot of harness and connectors, poor connection of terminals can cause various problems and damge of component.
Perform checking procedure as follows.
Check damage of harness and terminals : Check terminals for contact resistance, corrosion and deformation.
Check connecting condition of ECM and component connector : Check terminal seperation, damage of locking device and connecting condition between terminal and wiring.
Disconnect the pin which requires checking at male connector and insert it to the terminal at female connector for checking connecting condition. ( after checking, reconnect the pin at correct position. )
Is the problem found?
▶ Repair the trouble causing part and go to "Verification of Vehicle Repair".
▶ Go to "Signal Circuit Inspection ".
Check signal circuit voltage
IG KEY "OFF", ENGINE "OFF".
Disconnect IATS connector
IG KEY "ON"
Measure the voltage of terminal 3 of MAFS connector.
Specification : 4.8V~5.1V
Is the measured voltage within the specification?
▶ Go to "Component Inspection"
▶ Go to "2.Check short to ground in signal circuit" as follows.
Check short to ground in signal circuit
IG KEY "OFF", ENGINE "OFF".
Disconnect MAFS connector and ECM connector
Check continuity between MAFS connector terminal 3 and chassis ground.
Specification : Discontinuity ( Infinite Ω )
Is the measured resistance within the specification?
▶ Go to "Component Inspection".
▶ Repair short to ground in signal circuit and go to "Verification of Vehicle Repair".
IG KEY "OFF", ENGINE "OFF"
Disconnect MAFS connector.
Measure resistance of IATS component terminal 3 and 2, referring to resistance characteristic table of specification of General information.
Specification : Refer to Specification of General Information.
Is the measured resistance at certain temperature within the specified resisance range at the temperature?
▶ Go to "Verification of Vehicle Rapair"
▶ Replace MAFS ASSY' and go to "Verification of Vehicle Repair".
After a repair, it is essential to verify that the fault is corrected.
After connecting Scantool select "DIAGNOSTIC TROUBLE CODES(DTCs)" mode.
Clear recorded DTC using Scantool.
Drive the vehicle within DTC "Enable conditions" in "General information".
After selecting "DIAGNOSTIC TROUBLE CODES(DTCs)" mode and check if DTC is recorded again.
Are any DTCs recorded ?
▶ Go to the DTC guide of recorded NO. in Scantool.
▶ System operates within specification.
