P0112 Intake Air Temperature Sensor 1 Circuit Low Input
Description and meaning of DTC p0112
This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles. Although generic, the specific repair steps may vary depending on make/model. The IAT (intake air temperature) sensor simply measures the temperature of air thatis entering the engine. Intake air temperature is important because the higher theintake air, the higher the combustion temperatures. High combustion temperaturesresult in increased Nox (Nitrogen oxides) emissions. To keep these higher tempsfrom causing increased combustion temps, the intake air tubing should be intact,allowing the engine to "breathe" air that isn't sampled from the enginecompartment. The IAT measures air temp by using a thermistor, or a thermometer ofsorts. The thermistor is supplied 5 volts reference voltage from the PCM(powertrain control module) and a ground. Usually, when the air temperature is coldthe resistance in the thermistor is high and when the air temperature is warmer, theresistance decreases. This change in resistance changes the 5 V reference from thePCM, thereby informing the PCM of the temperature of incoming air. If the PCMnotices that the incoming air temp is unusually high, say, 300 degrees, when theengine temp is still relatively low, it will set a P0112.
p0112 diagnostic trouble code symptoms
There may be no noticeable symptoms of a P0112 code other than an MIL (MalfunctionIndicator Lamp). However, a emissions test may reveal higher Nox readings dependingon the type of IAT failure. Or the engine may ping under load, depending on thetype of IAT failure.
DTC p0112 - possible causes
Usually the P0112 is caused by a bad IAT (internally shorted or open or otherwise damaged),but it could also be:No reference voltage to the IAT sensor due to an open wireExcessively high intake air temperaturesShort to ground on signal circuitDamaged IAT connectorBad PCM
How to fix OBD-II diagnostic trouble code p0112
Hook up your scan tool or code reader and read the IAT reading. With a cold engine,the IAT should roughly match the coolant reading, since both will read ambienttemperature. If the IAT is reading excessively high, check the IAT connector fordamage. If you find none, unplug the IAT sensor and recheck the reading. It shouldnow read the minimum, around -20 deg. If it does, then replace the IAT sensor. But, if the reading is still high, unplug the sensor and check for resistance acrossthe two wiring harness terminals. If there is infinite resistance, then the PCMitself is bad. If the resistance isn't infinite, then check and repair the shortto ground on the signal circuit. Other IAT sensor and circuit related DTCs: P0095, P0096, P0097, P0098, P0099, P0110, P0111, P0113, P0114, P0127