• | 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 | P0110, P0111 |
Low Reference | -- | P0113 | P0113 | P0110, P0111 |
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 | 141°C (286°F) | -40°C (-40°F) | -40°C (-40°F)¹ |
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F)* |
* Internal ECM or sensor 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 |
• | DTC P0502 is not set. |
• | The engine run time is greater than 120 seconds or the ignition has been off for greater than 8 hours before vehicle is started. |
• | The vehicle speed is greater than 50 km/h (31 mph). |
• | The DTC runs continuously once the above conditions are met. |
• | DTCs P0106, P0107, P0108, P0117, P0118, and P0502 are not set. |
• | The calculated engine airflow is less than 15 g/s. |
• | The vehicle speed is less than 25 km/h (15 mph). |
• | The engine coolant temperature (ECT) is greater than 70°C (158°F). |
• | The engine run time is greater than 120 seconds, or the ignition has been off for greater than 8 hours before vehicle is started. |
• | The DTC runs continuously once the above conditions are met. |
The ECM detects that the IAT sensor is greater than 149°C (300°F) for greater than 10 seconds.
The ECM detects that the IAT sensor parameter is less than -38°C (-36°F) for greater than 4 seconds.
DTCs P0112 and P0113 are Type A DTCs.
DTCs P0112 and P0113 are Type A DTCs.
• | If the vehicle has set 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. |
Important: If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the sensor may be damaged.
⇒ | 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 the resistance Vs. temperature is 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 |