• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
IAT Sensor Signal | P0112 | P0113 | P0113* | -- |
Low Reference | -- | P0113 | P0113** | -- |
* Sensor damage may occur if the circuit is shorted to B+. ** Internal ECM damage may occur if the circuit is shorted to B+. |
Circuit | Short to Ground | Open | Short to Voltage |
---|---|---|---|
Operating Conditions: Engine operating in Closed Loop. Parameter Normal Range: Varies with ambient temperature. | |||
IAT Sensor Signal | 128°C (248°F), 0 Volts | -40°C (-40°F), 5 Volts | -40°C (-40°F), 5 Volts |
Low Reference | -- | -40°C (-40°F), 5 Volts | -40°C (-40°F), 5 Volts* |
* Internal ECM damage may occur if the circuit is shorted to B+. |
The intake air temperature (IAT) sensor is a variable resistor that measures the temperature of the air entering the engine. The IAT sensor has a signal circuit and a low reference circuit. The engine control module (ECM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit.
The following table illustrates the difference between temperature, resistance, and voltage:
IAT | IAT Resistance | IAT Signal Voltage |
---|---|---|
Cold | High | High |
Warm | Low | Low |
• | The engine is running. |
• | The DTC runs continuously once the above condition is met. |
• | The engine is running. |
• | The MAF is less than 56 g/s. |
• | The DTC runs continuously once the above conditions are met. |
The ECM detects that the IAT sensor voltage is less than 0.8 volts.
The ECM detects that the IAT sensor voltage is greater than 4.9 volts.
DTC P0112 and P0113 are Type A DTCs.
DTC P0112 and P0113 are Type A DTCs.
• | If the vehicle has sat overnight, the IAT sensor and the ECT sensor values should display within 3°C (5°F). |
• | High resistance on either the IAT sensor signal circuit or the IAT sensor low reference circuit may not set a DTC. |
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
⇒ | If greater than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM. |
⇒ | If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
Important: A thermometer can be used to test the sensor off the vehicle.
⇒ | If not within the specified range, replace the IAT sensor. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for engine control module replacement, setup, and programming |