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Matt, Engineer
Category: Subaru
Satisfied Customers: 21848
Experience:  Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
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Subaru forester 2001 turbo 2.0 boost error ........... .I

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Subaru forester 2001 turbo 2.0 boost error ...........
.I got CEL and checked the codes and got code 45 which to my belief is the Pressure sensor –Pressure exchange solenoid valve.I have checked in the engine bay and all hoses are connected and I reset the ECU and the code came back, I am hitting a fuel/boost cut at around five is like getting fuel cut as the boost comes in, this feels like I have suddenly stamped on the brakes while accelerating! How to fix this problem
Customer: replied 11 months ago.
are U there ?
Customer: replied 11 months ago.
Any help?


apologies for the wait

if you're getting a code 45 and the car is lacking power then yes I'd certainly agree that the MAP or boost pressure sensor is faulty

its attached to the inlet manifold via a little black rubber pipe and its not unheard of for these to split or crack and cause this code to flag up

so check this 1st and if the connection is OK then check the state of the wiring and electrical connector for corrosion and damaged insulation

if this is OK then replace the sensor

Customer: replied 11 months ago.
I've checked all wiring ,corrosion ,damaged insulation and even replaced sensor and still this code flagged up.. I have noticed once I raved above 4 rpm the cell code cleared but as soon it dropped to lower than 3.5 rpm is shows again..


Ok if thats all fine then I'd suggest to fit a boost gauge ( doesn't have to be a permanent fitting) so you can check if its making the 0.9 to 1 bar of boost its meant to

I'd first check all the high pressure hoses post turbo/s for any split hoses or cracked metal pipes, also check the ends of the intercooler as its not unheard of to pop the end caps off under high boost.

If this is OK then check the small vacuum lines to the turbo and its connected control solenoid on the bulkhead, any cracks or leaks can give turbo issues

Also have a feel around with your bare hands with the engine running to see if you can feel any escaping gas under your touch. Another method is to use a soap and water solution sprayed onto any suspect areas - if there's a leak it'll bubble up with the engine running

Also check that the vacuum hose running to the dump / turbo bypass valve is intact with no leaks as if the dump valve is opening prematurely you'll be losing all your boost

If this is OK then remove the high pressure intake hose after the turbo and have a feel of the turbine wheel - there should be no play radially at all - but a little bit of axial / end to end float is normal

one other possibility is that the wastegate actuator spring has gone soft so allowing the wastegate to open prematurely - if your actuator has a threaded end you can increase the preload on it to see if this improves things otherwise these units are quite cheap compared to a new turbo so it may be worth trying a replacement

Customer: replied 11 months ago.
once i removed the turbo i can feel shaft play , could it be the reason ?


if there's any play radially and signs of the compressor or turbine wheels touching the housing then yes that will be the reason as the turbo won't be spooling up as it should

if the play is axially then a small amoount is fine

Matt and 6 other Subaru Specialists are ready to help you
Customer: replied 10 months ago.
Hello Matt, after long time trying to fix this problems , I might have find something ; i have checked friends car {same car} and wiring connectors both black and brown colored and mine was quite high voltage which is 17 while the other car was 4.5 . Could it be the reason ?


if the connector you're talking about is the MAP sensor then yes this isn't right as there are a 5V device and if its that high then either there's a problem with the ECU earthing or the ECU is faulty

there should be some saml earth wires that run out of the wiring loom and are secured to the engine block with a small bolts and ring terminals

these need to be bright and clean

if this is OK then I'd suggest to send the ECU off for testing

Customer: replied 10 months ago.
Problem soooooolved !!! F*****N ECU.