1997 Mitsubishi Galant mass air flow sensor is believed to be going bad. Check engine light came on and the code was for the Intake Air Temperature sensor. Guy at auto zone suggested just replacing the Mass Air Flow Sensor, but I don't know how or where it is. He said I could probably do it myself. All help is greatly appreciated.

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

Here is the definition of the code.

P0101 GMC Description The Mass Air Flow (MAF) sensor is placed in the stream of intake air. It measures the intake flow rate by measuring a part of the entire intake flow. It consists of a hot film that is supplied with electric current from the Engine Control Module (ECM).

The temperature of the hot film is controlled by the ECM acertain amount. The heat generated by the hot film is reduced as the intake air flows around it. The more air, the greater the heat loss. Therefore, the ECM must supply more electric current to maintain the temperature of the hot film as air flow increases. The ECM detects the air flow by means of this current change.
Faulty mass air flow sensor
- Intake air leaks
- Dirty mass air flow sensor
- Dirty air filter
- Mass air flow sensor harness is open or shorted
- Mass air flow sensor electrical circuit poor connection
Read more: http://engine-codes.com/p0101_gmc.html#ixzz223ibNx6t

Read more: http://engine-codes.com/p0101_gmc.html#ixzz223i9HR3J

P0101 ISUZU - Mass Air Flow Circuit Performancehttp://engine-codes.com/p0101_isuzu.htmlForum CodePossible causes- Dirty mass air flow sensor
- Dirty mass air filter
- Mass air flow sensor harness is open or shorted
- Mass air flow sensor electrical circuit poor connection
- Intake air leaks
- Faulty mass air flow sensor
Tech notes 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

P0103 HYUNDAI - Mass or Volume Air Flow Circuit High InputPossible causes- Dirty mass air flow sensor
- Dirty mass air filter
- Mass air flow sensor harness is open or shorted
- Mass air flow sensor electrical circuit poor connection
- Intake air leaks
- Faulty mass air flow sensor
Tech notesBefore 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.
P0112 HYUNDAI - Intake Air Temperature Sensor 1 Circuit Low InputPossible causes- Dirty air filter
- Intake air temperature (IAT) sensor harness is open or shorted
- Intake air temperature (IAT) sensor electrical circuit poor connection
- Faulty intake air temperature sensor
When is the code detected?An excessively low voltage from the sensor is sent to ECM.

Tell me what code you are getting .
A barometric pressure sensor dose not work on its own .
You have the mass air flow sensor this is the first air sensor coming into the vehicle then you have an air temp sensor then what is called ECT engine coolant temp sensor .
The problem to me sounds like the MAP sensor manifold absolute pressure .You loss this the vehicle is not going to run to good.
If it wore the mass air flow it would cost the most the map is far less in price still not cheap the barometric sensor it likely a symptom of the real problem .
Check the gas flow in side the engine like EGR and EVAP systems to a vacuum thing .

P0103 - Mass or volume air flow circuit high input.

Symptoms: Engine stalls, running rough, excessive fuel consumption, excessive smoke from the tail pipe, check engine light on.

Possible Causes: Dirty mass air flow sensor, dirty mass air filter, mass air flow sensor harness is open or shorted, mass air flow sensor electrical circuit poor connection, intake air leaks, faulty mass air flow sensor.

P0116 - Engine coolant temperature circuit range/performance.

Symptoms: Check engine light on.

Possible Causes: Low engine coolant level, ECT sensor harness open or shorted, ECT electrical circuit poor connection, faulty engine coolant temperature sensor (ECT), faulty engine coolant thermostat.

manifold air temperture or intake air temperture sensor is bad . you can check the voltage on it when cold then w/hair dryer warm sensor up an check voltage if the resistance is more than 500 ohms then it is bad.

in the inlet air pipe from the air filter to the manifold

If the mass flow sensor was bad, the check engine light should of came on giving off an engine code. To remove the mass flow, disconnect battery neg cable, then pull of the wire harness and pull out mass. You will probably have to remove the air intake hose.

Does the Check Engine light come ON when this happens? Whenever the "Check Engine" light comes on, there is always a DTC (Diagnostic Trouble Code) stored in the ECM (Engine Control Module). You'll need an OBDII (On-Board-Diagnostics) scanner to retrieve any codes recorded/set in ECM. Once you do this and let us know what, if any codes are set, then we can go from there.
There are just too many possible causes for the problem you describe. Example: Sensors like the Mass Air Flow (MAF), Throttle Position Sensor (TPS), Manifold Absolute Pressure (MAP) sensor, Crank Position Sensor (CKP), Engine Coolant Temperature (ECT) Sensor, Intake Air Temperature (IAT) sensor, vacuum leaks, intake air hose leak, Wiring & connectors, clogged intake air filter, bad/contaminated fuel, malfunctioning injectors, poor ignition/spark or spark plugs or wires, Major Engine Mechanical problems, Out of Time, etc. etc. etc.