P1112 Possible Causes
- Faulty intake air temperature sensor
- Intake air temperature sensor harness is open or shorted
- Poor electrical connection in the intake air temperature sensor circuit
- Damaged powertrain control module (PCM)
How to Fix Code P1112?
Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
What Does It Mean?
Before replacing the mass air flow sensor, try replacing the air filter and cleaning the air flow sensor with mass air flow sensor cleaner. Reset the code and drive the vehicle. If the code returns, the mass air flow sensor may need to be replaced. Monitor the IAT on a scan tool. Look for sudden changes in the reading when the harness is shaken or the sensor is tapped.
Possible Symptoms
Illuminated check engine light (or service engine soon warning light)
P1112 Meaning
The IAT sensor is a thermistor device where resistance changes with temperature. The electrical resistance of a thermistor decreases as temperature increases and resistance increases as temperature decreases. The variable resistance affects the voltage drop across the sensor terminals and provides electrical signals to the powertrain control module (PCM) corresponding to the temperature.
Thermistor-type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so that the change in the passive sensor’s resistance causes a change in the total current flow. The voltage that drops across a fixed resistor in series with the sensor resistance determines the voltage signal to the PCM. This voltage signal equals the reference voltage minus the voltage drop across the fixed resistor.
The IAT sensor provides air temperature information to the PCM. The PCM uses air temperature information as a correction factor in calculating fuel, spark, and air flow.
The IAT sensor provides faster response time to temperature change than the ECT or CHT sensor.
Currently, there are 2 types of IAT sensors used, a standalone, non-integrated type and an integrated type. Both types function the same way, but the integrated type is incorporated into the mass air flow (MAF) sensor instead of being a standalone sensor.