GM Repair Questions? Ask a Mechanic for Answers ASAP
I would not see a faulty oxygen sensor causing for a lean code on both banks. I really would recommend that you do a fuel pressure test to verify that this truck is getting 60-66 psi of fuel pressure.
Hi, I'm James. I have seen two problems that generally set these codes.
First, the Mass Air Flow sensor becomes contaminated and reports a lower air flow to PCM than actual, so PCM does not command enough fuel. You either need to clean MAF sensor or replace it.
Second, the intake manifold gaskets leak air so that the MAF sensor data again is too low causing a lean condition. GM has developed a new gasket to repair this problem.