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P0099 is a diagnostic trouble code (DTC) for "Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic
P0099 is the OBD-II generic code that indicates that the engine control module (ECM) has detected a fault in the intake air temperature sensor 2 (IAT2). This code indicates that it is not operating in the normal sensor range and that the IAT2 has intermittent or erratic sensor input to the ECM.
The erratic or intermittent IAT input causes the ECM to not trust the input reading and substitutes its input to 70° F.
The intake air temperature sensor 2 is not accurate within 2 degrees when compared to the engine coolant and the mass air temperature sensors when the engine is cold started after the engine has been off for more than 5 hours.
The intake air temperature sensor 2 is not within specification range within 2 degrees of the sensor when compared to the mass air flow sensor when started warm and heat soaked from 10 seconds to 20 minutes.
Visually checks the electrical connections and wire harness to the intake air temperature sensor.
Scans and documents engine codes and checks freeze frame data for when the sensor failed.
Scans the IAT2 sensor and compares the output to be within specifications for when it fails in the freeze frame data to try and duplicate the sensor failure. They will lightly tap the sensor to see if the reading is erratic.
Disconnects the IAT2 sensor connector and verifies that the temperature reading goes below -4° F.
Shorts the two connector wires together to see if temperature readings go above 212° F.
While the connectors are shorted, they will do a wiggle test to see if any issues are found with the wiring or connections.
Using a multimeter to check that the ohms of the IAT2 sensor is within specifications while lightly tapping on sensor to see if the reading is erratic indicating a sensor internal failure.
Replaces the sensor if the sensor fails the wiggle test or is not within specifications.
The ECM will substitute a 70° F sensor input for the out of specification reading for the sensor.
The engine may run rough or hesitate if outside temperature is more than 10° F different from the 70° F the ECM uses as a substitute output.
The engine can hesitate and have a lack of power during acceleration depending on how different the outside temperature is from the default 70° F.
The engine will fail emission testing due to the Check Engine Light being on and the monitors not completed.
The IAT2 code P0099 can be caused from corrosion in the connector that is causing the connection to go in and out but stays in specification when it does work. Sometimes a sensor has loose connections internally that can be duplicated during testing and lightly tapping on the sensor.
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