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2001 Forester S
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Discussion Starter · #1 ·
I just purchased a 2001 Forester With the EJ251 engine (with the MAP sensor not the MAF).

I had a friend of mine replaced the head gaskets (oh surprise!) that were leaking. Two days after the repairs the CEL lit up. I had it scanned at the garage around the corners and came up with the P0101, P0102, P0108 and P0110 codes.

They are all related to the intake flow of air or something like that. My local garage thinks it got to do with the MAP sensor but I thinks it's more related to the fact that someone 'played' with the engine a couple of days ago.

Any ideas as to what could have triggers the CEL? It could be the MAP sensor but I think it would be a hell of a coincidence.....
 

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2008 Forester X Premium 5MT
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I would say check all the connections for the engine wiring harness to make sure none came loose. These would all have been undone for the repair.
 

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2001 Forester S
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Discussion Starter · #4 ·
After some researches on the web it appears it could be an intake air leak (possible after a replacement). How can I check if there is a leak or not?

Has anyone used the carb cleaner trick? Is there others ways?
 

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2001 Forester S
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Discussion Starter · #5 ·
Does anybody have an idea as to where to start? I already checked the wiring and the tubing and there is nothing wrong on this side.

Has this happened to someone before?
 

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1998 Forester
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Other methods

After some researches on the web it appears it could be an intake air leak (possible after a replacement). How can I check if there is a leak or not?

Has anyone used the carb cleaner trick? Is there others ways?
Use a propane torch (un-lit) to supply a bit of extra fuel around the suspected leak. The engine will run smoother due to the mixture being enriched by the propane. If you have post MAF sensor air getting in, the engine will run too lean.

You can also remove the MAF coupling pipe from the throttle body and MAF, apply a thin coating of silicone grease to the rubber surfaces and re-assemble it using new hose clamps to make sure it is sealed. The silicone aids the assembly and also seals up minor leaks.
 

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My 99-02 Subaru Shop Manual only lists code 0108 "Pressure Sensor Circuit High Input". This is an electrical fault for the Intake Air Pressure/Temperature Sensor meaning ECU sees high voltage input where it expects lower voltage.

This likely means disconnected, cut wire, or damaged sensor. Diagnostics are to search for the wiring/connector/sensor fault. You need a shop manual, circuit diagram, and diagnostics to locate the fault. As you suspect, it is likely due to intake manifold removal/installation for head gaskets work.

good luck
 

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2014 Impreza Ltd CVT
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This REALLY sounds like something mis-plugged, broken wire ( could be an internal break where the outside looks good ) or a missing ground.

P0101 and P0102 should never come up on your vehicle. They are for a MAF. Your 2001 is a MAP engine. This is why I think a mis-plug somewhere or ground. May also be the wrong ECU in the car.

P0108 and P0110 could make sense as one if the MAP circuit high, the other for the intake temp sensor ( right by the MAP but in the air filter housing ). Also leads me to think of a mis-plug, broken wire or missing ground.

I would start by checking continuity from each sensor plug back to the ECU plug.
 

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2000 Forester S
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Shot in the dark here: Check under your dash and look for green connectors that are plugged in. If they are, they shouldn't be. I had a similar issue with a mess of codes being thrown. When I unplugged the green connectors (due to advice from this forum), the codes went away. I'm just thinking someone may have plugged those connectors in thinking they were supposed to be together.
 

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Discussion Starter · #10 ·
I checked under the dash and the green connectors are not plugged in.

How do I check for continuity between the sensors and the ECU? How do a check for a missing ground?

I don't know if it could be of any help or if it's related. When I realease the clutch in first gear there is from time to time a vibration as if though the engine was about to stall. It also happen when engaging the second gear but with less amplitude. The clutch and pressure plate has been changed recently.

Could this be related to my CEL problem?

Thanks
 

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Check for wire continuity or discontinuity by disconnecting the sensor wires at the sensor and at the ECU. Manual and wiring diagram necessary to find connector location and wire color.

Once you've isolated the sensor wires, you ground engine side of one wire and check for ground presence or open on the ECU end of same wire. Good indication would be short to ground indicating the wire is connected. Bad indication would be an open (infinite resistance) indication; wire is broken somewhere. Check both wires same way.

If both wires indicate good, then ECU likely has an internal fault and new/used ECU necessary. Check car-part.com for a used replacement. I had to do this on a 97 Acura TL and paid $35 for a replacement ECU.

good luck
 

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2001 Forester S
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Discussion Starter · #12 ·
I'll get a test light and I'll check that out.

I also realize that the vibration problem only occurs when it's hoe outsie (above 25°C). When it's cold outside it doesn't seems to happens.

Today the temp gauge in the sash almost got to the red but everything sees to be fine.

Could the engine coolant temperature sensor be the cause here? I'll check for continuity on it anyway.
 

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Discussion Starter · #14 ·
I'm absolutely puzzled now. I borrowed a scan reader and I now pull a P0440 code. The P0101, P0102, P0108 and P0110 no longer appears!

I found the cause of the P0440 on the forum (a rotten gas tank neck which seems to be common).

Now I still have an issue with vibration when declutching...
 

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2008 Forester X Premium 5MT
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Try searching clutch judder/chatter/shutter it is common to some clutches including OEM.
 
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