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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15181
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Isuzu Npr: I have a 2012 Isuzu npr with a 6.0 gas engine, keeps

Customer Question

I have a 2012 Isuzu npr with a 6.0 gas engine, keeps on setting the same codes. The codes are p0171 and p0174 . It doesn't mater I'f the truck is running or not the codes will always set. Even with the key on engine off I can clear the codes, and the same codes will come back on. The truck runs great no problems with power. But engine light is on. I have replaced both up stream O2 sensors, the MAF sensor and cleaned the throttle body, was a little dirty, not bad. Check with carb cleaner looking for vacuum leaks. Nothing found. What am i missing
Submitted: 1 year ago.
Category: Chevy
Expert:  BOBBYSS replied 1 year ago.
Hello, my name is Bobby. Thanks for the question. Does the engine seem to idle fine all of the time?
Customer: replied 1 year ago.

It idles fine for us, but customer said it idled bad for him when it first came in it had a code of p0506, so I remover throttle body and cleaned it. Cleared the codes and took it on a drive cycle about 25 miles, just the p0171 and the p0174 came back. Idles fine and runs great. But I clear the codes with key on engine off and codes p0171 and p0174 come back without truck being started?

Expert:  BOBBYSS replied 1 year ago.
Can you tell me what the fuel trim readings are at idle and at 2500 rpm?