Iat sensor replacement - 1997 Mercury Villager

You can drive it a day or two before it resets because DTC P0116 is a Type B DTC. Which means this DTC runs only once a drive cycle . Where as a type A DTC runs continuous.
Conditions for Setting the DTC
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The control module detects a temperature difference between the ECT sensor and the intake air temperature (IAT) sensor of more than 100°C (180°F) at start-up.

OR

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The control module detects a temperature difference between the ECT sensor and the IAT sensor of more than 15°C (27°F) and the time elapsed cranking the engine without starting is more than 5 seconds.

OR

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The control module detects a temperature difference between the ECT sensor and the IAT sensor of more than 15°C (27°F). The vehicle must then be driven for 5 minutes over 40 km/h (25 mph). If the IAT sensor temperature decreases more than 5°C (9°F), an engine block heater was detected and the test is aborted. If the IAT sensor temperature does not decrease, an engine block heater was not detected and DTC P0116 will set.

Diagnostic Aids
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Inspect the ECT sensor terminals for corrosion and for engine coolant leaking through the sensor. Engine coolant that is leaking through the sensor will create a high resistance short to ground. This condition results in less voltage on the ECT sensor signal circuit, which is interpreted by the ECM as a warmer ECT.

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An IAT sensor that is skewed colder at various ambient temperatures due to greater resistance than is normal will increase the range between these two sensors. Measure and record the resistance of the IAT sensor at various ambient temperatures, then compare those measurements to the Temperature vs Resistance table. Refer to Temperature Versus Resistance .

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A slight to moderate resistance in the IAT sensor signal circuit or low reference circuit will increase the range between these two sensors. This condition results in a greater voltage on the IAT sensor signal circuit, which is interpreted by the ECM as a colder IAT.

Circuit/System Verification

1. Turn OFF the ignition.
2. Inspect the cooling system surge tank for the proper coolant level. Refer to Cooling System Leak Testing and Cooling System Draining and Filling .
3. If the ignition has been OFF for 8 hours or more, the ECT and the IAT should be within 15°C (27°F) of each other and also the ambient temperature. Turn ON the ignition, with the engine OFF, and use a scan tool to observe the IAT and the ECT sensor parameters.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the ECT sensor.
2. Ignition OFF for 90 seconds, test for less than 5 ohms of resistance between the low reference circuit terminal A and ground.
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If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, verify the scan tool ECT parameter is less than -39°C (-38°F).
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If greater than the specified range, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the ECM.

4. Install a 3-amp fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool ECT parameter is greater than 149°C (300°F).
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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.

5. If all circuits test normal, test or replace the ECT sensor.

Intake Air Temperature (IAT) sensor and Manifold Absolute Pressure (MAP) sensor are combined into a single assembly which is called Mass Air Flow (MAF) sensor. This MAF sensor is located on the air filter box near air filter hose, and is connected with a five wire connector. You cannot replace the IAT sensor alone. Instead a MAF sensor is replaced altogether.






Thank you for visiting Fixya.

Before I give you my answer I need to advise you, if you have an aftermarket/performance air intake, it will trip an IAT code pretty often, you will either have to live with it or try to find a "dummy" sensor (a fake IAT sensor designed for cold air intakes that will make your engine computer think the incoming air is a certain temperature) if you dont have an intake:

Chances are if the IAT code is coming up (assuming you do not have a cold air intake system) your IAT sensor is probably bad. There is a very long and tedious process of testing the sensor and the circuit for the sensor, but with the average price of a new IAT sensor being around $12 I pretty much always suggest just replacing the sensor. On your vehicle the IAT is part of the mass air sensor assembly, but can be replaced independanlty, and shouldn't be a very difficult replacement.

Intake Air Temperature Sensor Operation The Intake Air Temperature (IAT) sensor is a variable temperature sensitive resistor. Sensor resistance will change based on air temperature. The higher the temperature, the lower the resistance. The Engine Management System (EMS) provides a reference voltage and monitors the voltage drop between a fixed value internal resistance and the sensor resistance. This is called a voltage divider circuit.
IAT sensor values are used by the EMS to assist with the calculation of idle speed, fuel mixture and spark advance.
Inaccurate voltages from the IAT sensor may affect pulse-width, idle quality and tail pipe emissions. Intermittent signals may cause hesitation, stumble and surging. If an IAT sensor failure accompanies an Engine Coolant Temperature (ECT) sensor failure cooling fan operation may also be affected.
Some manufacturers' incorporate the Intake Air Temperature (IAT) sensor as part of the Mass Air Flow (MAF) sensor, or air flow meter. Refer to current service information for specific applications.
Related Symptoms The following symptoms can be caused by a faulty IAT sensor due to loose connections, bad grounds, high resistance in the circuit, or opens in the circuit.

• Extended crank time when the engine is cold
• Poor fuel economy
• Spark knock

P0113 - Intake Air Temperature Circuit High Input

What does that mean?
The powertrain control module (PCM) monitors the temperature of the air entering the engine. The PCM supplies a 5 volt reference voltage to the Intake Air Temperature (IAT) sensor. The IAT is a thermistor that varies resistance based on temperature. As the temperature increases, resistance decreases. Low temperature results in a high signal voltage. When the PCM sees a signal voltage higher than 5 volts, it sets this P0113 check engine light code.

Potential Symptoms
There will likely be no symptoms other than illumination of the Malfunction Indicator Lamp (MIL - Check Engine Light / Service Engine Soon).

Causes
A code P0113 may mean that one or more of the following has happened:
* Internally failed IAT sensor
* Faulty connection at IAT sensor
* Open in IAT ground circuit or signal circuit
* Short to voltage in IAT signal circuit or reference circuit
* IAT harness and/or wiring routed too close to high-voltage wiring (e.g. alternator, spark plug cables, etc.)
* Faulty PCM (less likely but not impossible)

Possible Solutions
First, if you have access to a scan tool, is there an IAT reading? If the IAT reading is logical then the problem is likely intermittent. If the reading is less than -30 degrees, unplug the connector. Install a jumper wire between the harness connector signal and ground circuits. The IAT temperature reading on the scan tool should be maxed out at the high end. For example it should be 280 degrees Farenheit or higher. If it is, the wiring is okay, and it may have been the connection. If it isn't install the jumper wire between the IAT signal circuit and the chassis ground. If now the IAT reading on the scan tool is maxed out then check for an open in the IAT ground circuit. If you get no reading at all on the scan tool, it's likely that the sensor signal is open or the 5 volt reference is missing. Check using a DVOM (digital volt ohm meter) for a 5 volt reference. If it's there, then unplug the connector at the PCM and check for continuity on the IAT signal circuit between the PCM connector and the IAT connector.

Hope this help (remember rated this).

the iat sensor is located in the fresh air duct connected to the air filter in front of the fuse/relay control panel. to remove the iat sensor, renive the air filter cover and using a pair of wire cutters remove the small steel band holding the sensor in place. then by pulling on sensor it will come out. when replaceing sensor be sure to install new metal ring on new sensor to secure it in place.

the IAT sensor is part of the Mass Airflow sensor. here is a picture of that sensor.

A code P0113 may mean that one or more of the following has happened:

• Internally failed IAT sensor
• Faulty connection at IAT sensor
• Open in IAT ground circuit or signal circuit
• Short to voltage in IAT signal circuit or reference circuit
• IAT harness and/or wiring routed too close to high-voltage wiring (e.g. alternator, spark plug cables, etc.)
• Faulty PCM (less likely but not impossible)

Go to Autozone.com type in IAT sensor or MAF sensor for your vehicle, then click on vehicle repair guides, that gives you some information that could help you more.