• | 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 provide an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
IAT Sensor 1 Signal | P0112 | P0113 | P0113 | P0113 |
IAT Low Reference | -- | -- | -- | -- |
Circuit | Short to Ground | Open | Short to Voltage |
---|---|---|---|
Operating Conditions: Ignition ON or Engine Running Parameter Normal Range -39 to +120°C (-38 to +248°F) | |||
IAT Sensor 1 Signal | 149°C (300°F) | -40°C (-40°F) | -40°C (-40°F)* |
IAT Low Reference | -- | -- | * |
*Internal ECM or sensor damage may occur if the circuit is shared to B+ |
The intake air temperature (IAT) sensor 1 is a variable resistor. The IAT sensor measures the temperature of the air entering the engine. The engine control module (ECM) supplies 5 volts to the IAT signal circuit, and a ground for the IAT low reference circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the IAT signal circuit.
• | The engine is running. |
• | DTC P0112 and P0113 run continuously. |
The IAT Sensor parameter is warmer than 148°C (299°F) for greater than 1 second. This is equal to or less than 0.10 volt on the IAT signal circuit as measured by the ECM.
The IAT Sensor parameter is colder than -39°C (-38°F) for greater than 1 second. This is equal to greater than 4.8 volts on the IAT signal circuit as measured by the ECM.
• | DTC P0112 and P0113 are Type B DTCs. |
• | Diesel particulate filter (DPF) regeneration is inhibited. |
DTC P0112 and P0113 are Type B DTCs.
• | With the ignition ON and the engine OFF, if the engine is cold, a properly functioning IAT sensor will gradually increase the scan tool IAT Sensor parameter. This is due to the heat that is generated by the mass air flow (MAF) sensor heating elements. |
• | Depending on the ambient temperature, an IAT sensor signal circuit or low reference circuit that is shorted to the MAF sensor signal circuit can cause a DTC P0113 to set. This condition can cause a rapid fluctuation in the IAT Sensor parameter. |
• | An IAT low reference circuit that is open can cause the IAT Sensor parameter response to be sluggish. This condition may not necessarily set a DTC. |
• | An IAT sensor signal circuit that is shorted to the MAF sensor ignition circuit can cause a DTC P0113 to set. |
• | Verify that any electrical aftermarket devices are properly connected and grounded. Refer to Checking Aftermarket Accessories. |
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
⇒ | 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 MAF sensor low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
⇒ | If warmer than the specified range, test the signal circuit terminal 5 for a short to ground. If the circuit tests normal, replace the ECM. |
⇒ | If colder 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. |
Measure and record the resistance between the signal terminal 5 and the low reference circuit terminal 4 at the IAT sensor. Compare the value to the Temperature Vs Resistance table. Refer to Temperature Versus Resistance.
• | Control Module References for ECM replacement, setup, and programming |