Technical Description of OBD-II Trouble Code
The circuit for Intake Air Temperature Sensor 1 is experiencing intermittent issues.
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code that is applicable to all vehicles manufactured from 1996 onwards (including Ford, Mazda, Mercedes Benz, etc.). Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
A stored code P0114 indicates that the powertrain control module (PCM) has detected an intermittent input signal from the intake air temperature (IAT) sensor circuit.
The PCM uses the input signals from the IAT sensor and the mass airflow (MAF) sensor to calculate the fuel delivery and ignition timing strategy. Since maintaining the correct air/fuel ratio (typically 14:1) is crucial for engine performance and fuel efficiency, the input from the IAT sensor is highly important.
The IAT sensor is usually threaded directly into the intake manifold, but it is more commonly inserted into the air inlet pipe or air cleaner box. Some manufacturers also integrate the IAT sensor into the MAF sensor housing. Regardless of its location, it must be positioned in a way that allows ambient air, drawn into the intake manifold through the throttle body, to continuously and consistently flow across it while the engine is running.
The IAT sensor is typically a two-wire thermistor sensor. The resistance of the sensor varies based on the temperature of the air flowing across the cold wire element. Most OBD II equipped vehicles use a reference voltage (usually five volts) and a ground signal to complete the IAT sensor circuit. The varying resistance levels in the IAT sensor element cause voltage fluctuations in the input circuit. The PCM interprets these fluctuations as changes in the intake air temperature.
If the PCM detects a certain number of intermittent signals from the IAT sensor over a specific period of time, it will store a code P0114 and may illuminate the malfunction indicator lamp.
Severity & Symptoms
Since the IAT sensor signal is used by the PCM to calculate the fuel delivery strategy, a code P0114 should be considered severe.
Symptoms of a P0114 code may include:
Causes
Possible causes for this engine code include:
Diagnostic and Repair Procedures
It is always a good idea to check for technical service bulletins (TSB) specific to your vehicle when diagnosing a code P0114. There may be a known issue with a known fix provided by the manufacturer, which can save you time and money during the diagnosis process.
When dealing with a code P0114, it is recommended to have a suitable diagnostic scanner, a digital volt/ohmmeter (DVOM), an infrared thermometer, and a reliable source of vehicle information (such as All Data DIY) at your disposal.
Connect the scanner to the vehicle’s diagnostic connector and retrieve the stored trouble codes and freeze frame data. It is advisable to write down this information in case it is needed later. Clear the codes and test drive the vehicle. If the code is immediately reset, proceed with the diagnostic process.
Most professional technicians start by visually inspecting the wiring and connectors related to the IAT sensor (don’t forget to check the air filter and air inlet pipe). Pay close attention to the sensor connector, as it is prone to corrosion due to its proximity to the battery and coolant reservoir.
If the system wiring, connectors, and components appear to be in working order, proceed by connecting the scanner to the diagnostic connector and accessing the data stream. By narrowing down the data stream to include only relevant data, you can receive a faster response. Use the infrared thermometer to verify that the IAT reading on the scanner accurately reflects the actual intake air temperature.
If the reading is incorrect, consult your vehicle information source for IAT sensor testing recommendations. Use the DVOM to test the sensor and compare the results with the vehicle specifications. Replace the sensor if it fails to meet the specifications.
If the sensor passes the resistance test, check for a sensor reference voltage and a ground. If either of these signals is absent, repair the open or shorted circuit and retest the system. If the reference voltage and ground signals are present, obtain an IAT sensor voltage to temperature chart from your vehicle information source and use the DVOM to test the sensor’s output voltage. Compare the voltage with the voltage to temperature chart and replace the sensor if the actual findings deviate from the maximum recommended tolerances.
If the actual IAT input voltage falls within the specifications, disconnect the electrical connectors from all related controllers and use the DVOM to test the resistance and continuity of all system circuits. Repair or replace any circuits that are found to be open or shorted, and retest the system.
If the IAT sensor and all system circuits are within the recommended specifications, suspect a defective PCM or a PCM programming error.
Additional diagnostic notes:
Related IAT sensor and circuit trouble codes: P0095, P0096, P0097, P0098, P0099, P0110, P0111, P0112, P0113, P0127
