Parts & Assemblies

All info for 2009/2010 Impreza Diesel Euro 4 model unless noted otherwise.

OBD Socket, Body Integrated Unit (BIU)

Mass air flow & inlet air temperature sensor

5 pins: 4 x ECU, 1 x power supply

Similar to this “Air Flow Meter” DENSO product image:

Variable geometry turbocharger control valve, common rail pump suction control valve

Glossary Links:

Manifold air pressure & manifold air temperature sensor; fuel temperature sensor

Manifold air pressure (MAP) & manifold air temperature sensor: 4 pins, connected to ECU
Fuel temperature sensor: 2 pins, ECU

Diesel Particulate Filter (DPF)

Glossary: DPF (Diesel Particulate Filter)
DPF casing contains oxidation catalyst (left portion, roughly 1/3 length) and actual DPF.

Exhaust Gas Temperature (EGT) Sensors

Glossary: EGT (Exhaust Gas Temperature)

Note: Only 2008/2009 Legacy/Outback models are fitted with open-type (unmanaged) DPF. These are easy to recognize as they do not have any EGT sensors nor DPF pressure difference sensor.

DPF Pressure Difference Sensor

Larger diameter piping is connected to DPF inlet (downstream catalyst), smaller diameter one to DPF outlet.

Note: On Euro 5/6 models, DPF pressure difference sensor is mounted on engine, below vacuum pump (left bottom in picture above).

EGR cooler

Euro 4, towards front at right cylinder bank. EGR cooler, engine harness connector.

Euro 5+

Easy to recognize as the intake manifold is made of black resin material, supposedly 1.5 kg lighter compared to Euro 4’s aluminum casting. Euro 6 is similar.
2012 Euro 5 engine bay


Further parts: DENSO – Diesel Engine Management System


12 responses to “Parts & Assemblies

  1. Hallo!. Can you tell me, if the engine idle rpm is not steady (hunting) ,is it the MAP sensor needs replaced?
    I`m yet to get the diag tool (tactrix cable) and at the service they cleaned the intake manifold but still the hunting is there, from time to time thou!


    • Hi, haven’t heard about such idle hunting yet. Not sure about MAP sensor. Could be caused by injectors or fueling system in general. Data logging might reveal the cause. Everything else feels and sounds normal? Which model & model year?


  2. Hi!. Sorry about the late reply. The car is a 08 Legacy euro 4. There is a history with the fuel injectors, they were supposely replaced under warranty but I have no feedback about which one or how many were replaced.
    By the way, you are the first to ask about the car “feel”. It feels moody, at times the engine response is flaweless, at times is sluggish and black smoke comes out from exhaust. I have been careful about the fuel quality but is not that. I can`t link the behaviour to anything yet and at the service the answer is the injectors are OK.
    You are right, data logging will reveal the cause.
    Thank you for the quick response


    • Hopefully standard data logging can reveal some hints but there’s no guarantee. Send in some files when you’re ready, there’s no charge until we say so. Good luck!


  3. Hello there,

    My question is that sometimes, when I start the engine white smoke comes out from the mufflers, and the cars smells like a barell paraffin. I had diesel cars before, normal Turbo diesels, but this smell was is totally different. What should be the problem? EGR valve was not cleaned I think and there is 150.000 km = 93.000 miles in the car.



  4. Hello,
    I have a impreza diesel euro 5.Sometimes keep the engine in(no power for 1 sec.) between 2500 and 3000 . what may be the problem of this?EGR is changed .and fuel sensor under collector also new.problem remains.
    Thanks for you replay.
    Best regards Huyck


  5. Anyone know the part number for the Suction Control Valve and where I could source one?


  6. Hi. i have a impreza 2011 diesel euro5 with broken engine, is i it posible to put in a euro4 engine?
    I have a complete car to take parts from.


    • Szia Endre! Lehet, de motorvezérlőstől együtt kell cserélni+DPF-et is cserélni kell.


    • Hi! Possible, haven’t seen this personally, but probably more work than putting Euro 5 core engine into Euro 4 car (several examples working, Subaru does this as well AFAIK).
      Euro 5 has different harness, turbo, more sensors (turbo lift sensor, oil level sensor), ECU connector etc. Injector characteristics also differ. Since calibration and sensors are ECU software dependent, ideally these things should match ECU type. Changing ECU type is not feasible IMHO.


  7. Do you have part number or pictures of the crank angle sensor? And any info on replacing it?


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