iPhone 4 Proximity sensor not working logic board problem ! & iphone

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iPhone 4 Proximity sensor not working logic board problem ! & iphone

On March 28, 2015, Posted by , In iPhone, With Comments Off on iPhone 4 Proximity sensor not working logic board problem ! & iphone

Hi, hopefully someone will be able to to be helped me here. I purchased a used iphone 4 online and in the description it stated it had a new screen fitted but the proximity sensor didnt work. I assumed it would be a very simple fix and set about trying to fix it today but after 3 hours and literally trying everything i could try it still doesnt work.

What ive tried so far:
1. Several new screens including original apple screen from another phone.
2. Colored in the small window above the spaeaker grill Along with black marker (common fix)
3. Placed black electrical tape over the window (another common fix)
4. Several new proximity flex cables (all tested and confirmed working on another phone)
5. Factory reset the iphone

What Ive discovered:
Looking at the logic board under a microscope i found a missing component directly above the power button flex connector. Checking the schematic i found on here its a capacitor (i presume) labelled C4_PMU. I replaced this component Along with another one from a spare iphone 4 logic board but still the proximity sensor doesnt work title=madtitle=madtitle=mad

Does anyone know if this capacitor has anything to do Along with the prox sensor or has anyone got any other suggestions i can try.


No Comment so far:

  1. Phil says:

    Along with white new screens I uses this trick (Along with black it not wanted)

  2. wagny says:


    Did you tryed to place a film on it?

  3. qwerty305 says:

    Those solutions above are really accurate. ^ ^
    Maybe the housing and the screen are surely connecting properly. No gap or space between them. Or the screen comes off is one of those problems.
    Good luck, bro.

  4. julianz says:


    Check this picture i have solved this problem by jumper missing resistor marked marked in blue.

  5. TechGuru says:

    Ive already tried all the suggestions mentioned as stated in my first post and checking the logic board I can confirm that resistor in the picture is present on mine.

    The only component that was missing (obviously damaged by a finger nail or pry tool) and which i have now replaced is a capacitor labelled C4_PMU.

  6. Bo-Rens says:

    By me is proximity sensor problem too.
    Phone was water damaged…
    …now is all repaired, but problem Along with in-call face detect still title=frown
    I have test the mainboard inside 100% working frame Along with display but still nothing.
    Proximity connector was measured and compared Along with another mainboard and all looks fine.
    Infra led in call works too.
    No solution for me?