Tip & How-To about Mercedes-Benz E-Class

Intake air temperature sensor on engines

1.2) IAT - Intake Air Temperature sensor

What is it? The intake air temperature sensor is a small electrical device (Thermistor - temperature dependent resistor) that consists of a small bead on a loop of wire held within a plastic safety frame.

Where is it located? Is most often found associated with the MAF (AMM) in the air ducting immediately after the air filter/cleaner box. On cars without a MAF (a manifold pressure sensor - MAP usually takes on the role) the IAT may be sited nearer the throttle opening in the air ducting. It has only two wires that make connection with it. However, when located with the MAF, a combined multi-pin plug will serve both devices.

How does it work? It measures the intake air temperature by simply measuring the resistance in the thermistor bead on the wire. The IAT is most commonly located alongside the MAF. The IAT thermistor sends a signal proportionate to the air temperature (if the usual NTC thermistor the resistance drops with increasing temperature; if PTC type them resistance increases with increasing temperature). With the engine running, fresh air is drawn through the ducting and cools the heated MAF. The temperature of the air, in conjunction with its ability to cool the MAF allows the ECU to determine the mass of air entering the engine and thereby to select the appropriate amount of fuel by adjusting the injection times.

Symptoms of a faulty IAT
Associated OBD2 error codesDTCs: P0110 - P0114; P0127

  • Higher erratic idle speed - If the IAT is at fault the ECU cannot accurately work out the mass of air entering the engine and may use a default value that is inappropriate.
  • Erratic engine - In the absence of signals from the IAT and MAF the ECU takes readings from the TPS and other sensors and this causes a rough running engine.

How to Check? Unplug the device from the duct and check that it is clean. Put a voltmeter across the contacts and measure the resistance due to the ambient air temperature. If you then breathe on it, raising the local air temperature around the probe, you will see the resistance change as a consequence. You are looking for a change in resistance in line with a change of air temperature. If there is infinite resistance, consistent with a broken circuit, or there is no measurable response to change in air temperature then the IAT is faulty.

How to Fix? Replace it


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03 Nissan Altima showing codes P0304,P0102,P0154,P0113 what are they and how do i repair the problems.


Hi Chris.

p0304 = Number 4 Cylinder Misfire Detected

Faulty spark plug 4
Clogged or faulty fuel injector 4
Faulty ignition coil 4
Fuel injector 4 harness is open or shorted
Fuel injector 4 circuit poor electrical connection
Ignition coil 4 harness is open or shorted
Ignition coil 4 circuit poor electrical connection
Insufficient cylinder 4 compression
Incorrect fuel pressure
Intake air leak

The P0304 code means that the cylinder 4 is misfiring or is randomly misfiring. Start by checking for intake leaks an if no leaks are found the next step is to replace the spark plugs on cylinder 4.


p0102 = Mass or Volume Air Flow Circuit Low Input

Faulty mass air flow sensor
Intake air leaks
Dirty mass air flow sensor
Dirty mass air filter
Mass air flow sensor harness is open or shorted
Mass air flow sensor circuit poor electrical connection

Before replacing the mass air flow sensor, try replacing the air filter and cleaning the air flow sensor with low compress air or mass air flow sensor cleaner.
Reset code and drive vehicle.
If the code comes back, it may be necessary to replaced the mass air flow sensor.


p0154 = O2 Sensor Circuit No Activity Detected Sensor 1 Bank 2

Faulty Front Heated Oxygen Sensor Bank 2
Front Heated Oxygen Sensor Bank 2 harness is open or shorted
Front Heated Oxygen Sensor Bank 2 circuit poor electrical connection
Inappropriate fuel pressure
Faulty fuel injectors
Intake air leaks may be faulty
Exhaust gas leaks

Replacing the Front Heated Oxygen Sensor Bank 2 usually takes care of the problem.


p0113 = Intake Air Temperature Sensor Circuit High

Faulty Intake Air Temperature (IAT) sensor
Dirty air filter
Intake Air Temperature (IAT) sensor harness is open or shorted
Intake Air Temperature (IAT) sensor circuit poor electrical connection

The Intake Air Temperature (IAT) sensor is built into mass air flow sensor or in some vehicles mounted to the air filter duct housing. The sensor detects intake air temperature and transmits a signal to the Engine Control Module (ECM).The temperature sensing unit uses a thermistor which is sensitive to the change in temperature. Electrical resistance of the thermistor decreases in response to the temperature rise. The Intake Air Temperature signal is used as an input for various systems in the vehicle.



Hope this helps
FYT

http://www.autocodes.com/make/nissan

Mar 26, 2017 | Nissan Cars & Trucks

1 Answer

undefinedas replacement on civic 98 sensor p0113


Possible causes for this code are: - Faulty Intake Air Temperature (IAT) sensor
- Dirty air filter
- Intake Air Temperature (IAT) sensor harness is open or shorted
- Intake Air Temperature (IAT) sensor circuit poor electrical connection. this code sets when: - An excessively high voltage from the sensor is sent to ECM. Usual Possible symptoms - Engine Light ON (or Service Engine Soon Warning Light) P0113 1998 Honda Civic Description The Intake Air Temperature (IAT) sensor is built into mass air flow sensor or in some vehicles mounted to the air filter duct housing. The sensor detects intake air temperature and transmits a signal to the Engine Control Module (ECM).The temperature sensing unit uses a thermistor which is sensitive to the change in temperature. Electrical resistance of the thermistor decreases in response to the temperature rise. The Intake Air Temperature signal is used as an input for various systems in the vehicle.
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Sep 24, 2014 | 1998 Honda Civic

2 Answers

What does Code P0113 mean?


http://repairpal.com/obd-ii-code-p0113

Jul 09, 2014 | 1998 Ford Expedition

1 Answer

iat sensor high input


What is it? The intake air temperature sensor is small electrical device (Thermistor - temperature dependent resistor) that consists of a small bead on a loop of wire held within a plastic safety frame.


Where is it located? Is most often found associated with the MAF (AMM) in the air ducting immediately after the air filter/cleaner box. On cars without a MAF (a manifold pressure sensor usually takes on the role) the IAT may be sited nearer the throttle opening in the air ducting. It has only two wires that make connection with it. However, when located with the MAF, a combined multi-pin plug will serve both devices.


How does it work? It measures the intake air temperature by simply measuring the resistance in the thermistor bead on the wire. The IAT is most commonly located alongside the MAF. The IAT thermistor sends a signal proportionate to the air temperature (if the usual NTC thermistor the resistance drops with increasing temperature; if PTC type them resistance increases with increasing temperature). With the engine running, fresh air is drawn through the ducting and cools the heated MAF. The temperature of the air, in conjunction with its ability to cool the MAF allows the ECU to determine the mass of air entering the engine and thereby to select the appropriate amount of fuel to use by altering the injection times.


Symptoms of a faulty IAT


  • Higher erratic idle speed - If the IAT is at fault the ECU cannot accurately work out the mass of air entering the engine and may use a default value that is inappropriate.
  • Erratic engine - In the absence of signals from the IAT and MAF the ECU takes readings from the TPS and other sensors and this causes a rough running engine.


How to Check? Unplug the device from the duct and check that it is clean. Put a voltmeter across the contacts and measure the resistance due to the ambient air temperature. If you then breathe on it, raising the local air temperature around the probe, you will see the resistance change as a consequence. You are looking for a change in resistance in line with a change of air temperature. If there is infinite resistance, consistent with a broken circuit, or there is no measurable response to change in air temperature then the IAT is faulty.


How to Fix? Replace it

Dec 11, 2010 | 2002 Mitsubishi Galant

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