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needs more cowbell
95L, 07 2.5i, R6
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That still doesn't help me!

It might if you'd check under your hood for the map sensor. If you're unsure of what a map sensor is you need to get someone with more automotive experience to help you check it out in person.
 

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01 Impreza RS
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Discussion Starter · #7 ·
I know one of the sensors I mentioned is on the intake manifold and the other is mounted on the passenger side shock tower. I don't know which part I need to replace.
 

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needs more cowbell
95L, 07 2.5i, R6
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You also need to check to be sure the sensors are getting the correct input voltage. The map sensor should have a 5v source voltage if I remember correctly. The map sensor also connects to the intake manifold through a vacuum hose, or it can be screwed directly to the intake manifold.

I looked up that code and it says "Pressure Sensor Circuit Low Input
"

Is your car running poorly or having any problems or is the check engine light coming on with no obvious problems?
 

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01 Impreza RS
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Discussion Starter · #9 ·
It loses power on and off. It's not completely falling on its butt everytime I touch the gas. About half of the time. Whatever monitors the intake airflow isn't working properly maybe? Yes the check engine light is on. I also got P0031 which means the front o2 is bad.
 

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Oh.. ok.. Now I get your confusion.
MAP = Manifold Absolute Pressure.
Therefor, it's the one on your Manifold.
Teh one on your shock tower is your atmo pressure sensor. Not a MAP sesor.
true, yet if one sensor reads off compared to another, it will still run like piss.
example, adding 10psi makes the map read 24.7psi, while the atmo reads 14.7. This will throw a code as well.Both must equal each other
 

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Discussion Starter · #15 ·

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Do you have a multimeter (you know, to read voltage and resistance) and stuff? It's check for the 5V on the MAP sensor. It's probably plugged in right next to or on the throttle body. (I'm not sure because i have an STI.) I'm not sure exactly what the Atmospheric Pressure Sensor uses for voltage readout, but it should be pretty close to 5V, depending of course on what the pressure is where you live.
Check the input voltage first, and then the output. If the input is good, and the output is bad, it's gotta be the sensor. If the input is bad, well you know, it's something further up the line.
When troubleshooting electrical problems with any type of test equipment, in this case a multi/volt meter, always "half split" the circuit. Example: check half way in the circuit, and then check again in the direction of the bad reading. Its the easiest and most accurate method.

P.S. if you don't have a multimeter, you can buy one at any auto parts store or radio shack type place. They are anywhere from $20-$300, and yes, the $25 ones are just fine if you don't need all the bells and whistles.

Let us know what you found out.
 

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incorrect.

a MAP sensor, by name, Manifold Absolute Pressure, is clearly in a manifold. the barometric sensor on the strut tower is not a MAP sensor. It is a barometric sensor. Same job (as-in reading absolute pressures), different location, does different things.

OP needed to replace the MAP sensor which has the air intake temperature sensor built in to it. It was plain english in the code, but this thread made it extremely painful.

I can't believe how many times i face palmed in this thread.










The MAP sensor measures the amount of air in the intake manifold for fueling. the barometric sensor on the strut tower is for elevation adjustments. That way when you drive from sea level to mt everest the car is happy as a clam and makes adjustments on the fly. without the barometric sensor your car would start to run like shit once you were halfway to everest. without the barometric sensor you would need to restart the car several times on your trip for it to maintain drivability.
 

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2000 RS Coupe
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Literally just went through this:
 
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