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rpmdiag, Tech and Instructor
Category: Chevy
Satisfied Customers: 6874
Experience:  Since 1975
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2006 Silverado 1500 5.3l engine. I have p0172 and p0175. on

Customer Question

2006 Silverado 1500 5.3l engine. I have p0172 and p0175. rich on both banks. all 4 02 sensors are operating within range of 200-800mv. I have 62psi fuel pressure at idle. and MAF sensor also appears to be operating properly. I installed new maf sensor and the reading at idle was the same as it was before with the old one. long term fuel trim on both banks is -19.5. did not find any blockages in air intake system. after the truck sits for a few hours or overnight, it is hard to start. long cranking and stalling type symptoms. after it runs for a few minutes, I can shut it off and it starts right back up
Submitted: 20 days ago.
Category: Chevy
Expert:  rpmdiag replied 20 days ago.

Hi, I'm Ron and I will be helping you today.
Stand by for a moment while I prepare your answer.

Expert:  rpmdiag replied 20 days ago.

Rich codes can be caused by a bad fuel pressure regulator or a filth air or blockage in the intake plumbing filter.

Rarely would 2 O2 sensors go out at the same time, but this problem can also be a bad PCM, so checking that against a lab scope would be the next test.

Thanks, Ron

Expert:  rpmdiag replied 20 days ago.

If you are satisfied with my answer, I would greatly appreciate a 5
star rating now and I will still assist you after you have rated me
too if another question pops up. I don’t get credit for helping you
until you rate me.
Thanks again, Ron