Is there any certified GM techs in the group? U0109 is driving me insane.

[Jmix91]

connect a fuel pressure tester on the rail and see if it is actually high or not, that should point you one way or another.

The scanner reads below 4 volts

 

[Doubeleive]

The scanner reads below 4 volts

So.. low voltage? should be 5+?, not familiar but most stuff is usually 5v or more

 

[Jmix91]

No the code reads high voltage. Lo

Low voltage is below .4 volts

High voltage is above 4 volts

I know it’s weird and very confusing.

 

[swathdiver]

That might be my problem. I’ll feel more comfortable once I get rid of the new CEL P0193. I had replaced the fuel pressure sensor like I said before and then “fixed” the stalling problem now I have a P0193

Can you view the failure records with your scan tool?

From the shop manual for P0193: