Author Topic: Check engine light (low boost pressure)  (Read 1284 times)

Kent Morrison

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Check engine light (low boost pressure)
« on: January 20, 2023, 06:40:42 PM »
My check engine light comes on randomly.  When I check the code it always tells me it is low boost pressure. I have changed fuel filters, air filter, as well as the boost pressure sensor.  I also had the turbo checked and was told it was working the way it should.  Nothing I have done has solved the issue. The check engine light does not always come on and it never a stays on. When it does come on it is always when I am asking for power. As soon as I take my foot off the throttle the light goes out. I can see the boost pressure while I’m driving and it runs between 29 and 31when asking for power. Is there something that I am missing? I have a C9 Cat engine.
« Last Edit: January 20, 2023, 06:49:16 PM by Kent Morrison »
2005 Monterey
CAT C9

David T. Richelderfer

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Re: Check engine light (low boost pressure)
« Reply #1 on: January 20, 2023, 10:04:17 PM »
2004 Beaver Marquis Sapphire

I had a dream... then I lived it!

Eric Maclean

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Re: Check engine light (low boost pressure)
« Reply #2 on: January 20, 2023, 10:05:43 PM »
Does yours have a Racor fuel / water separator with the clear prescreen assembly attached?
If so your problem may be air being sucked into the fuel system at the O rings on that fuel separator
To verify this you can install ( temperately ) a clear piece of hose into the fuel return line and watch for fuel bubbles
Air in the fuel rail will cause low power conditions and resulting low boost  as well as injector failures over time as the injectors rely on the fuel to cool them

Hope this helps
Eric
1997 Patriot Yorktown
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