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Discussion Starter · #1 ·
I installed my sonnax line booster yesterday and noticed a difference in the shifts. Today my check engine light came on, I plugged in my DSP and it said low transmission fluid pressure. I checked the fluid and it's good. I took the sonnax off and the check engine light is still on. Anyone else have this happen?
 

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Can't say I've had that issue. Did you check the level what it was warm? All the sonnax does is increase the line pressure to give you more pressure on the clutches, so unless you have a low fluid level due to the increased pressure or a faulty sensor, I don't know what it would be.
 

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Discussion Starter · #3 ·
I checked the level when it was warm and it looked good. I checked it a couple hours later when it was cold and it looked good then too. Do you know where the pressure sensor is located? Its just weird to me that it says low pressure, I would understand a hi pressure alarm a little more.
 

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Check the cooler line filter. Mine threw a similar code and the filter was found to be clogged. Maybe the increased pressure stirred up something and it clogged the filter.
 

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Id check the filter first...I can see the sensor going bad but, not it its throwing a low fluid code.
 

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Yes reset the PCM and you should be fine. Unhook the negative battery cable for about 30 minutes.

I believe the way the sonnax works is that it is a resistor that alters the pressure sensor's signal to the pcm, making it appear lower than it actually is, and then as a result the PCM is supposed to add line pressure to compensate. The PCM thinks it's bringing the pressure back to normal, but since it's a false low pressure reading it ends up at a higher line pressure than it was before.

Supposedly this is a temporary effect. After some time the PCM (through other sensors, etc...) will recognize the actual line pressure, and will adjust the pressure back down to get back to stock actual line pressure.
 

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Discussion Starter · #10 ·
Thanks guys, the filter looks good. I unhooked the battery for about an hour while I was getting ready to leave and I drove about 30 minutes to a buddies house for the Super Bowl and so far so good. It definately shifts harder, feels more like it should.
 

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i get that code every once in awhile..interesting enough, i only get it when my tstat throws a 'too cold' issue..and more funny, only the dsp picks it up... when I use a more advanced scanner, it doesn't pick up the low pressure code so I think it's a quirk in the dsp whenever i throw any other code...
 
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