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P0171 Lean Fuel Condition in 2000 Chevrolet C/K1500 5.3L V8 - Diagnosis & Repair Tips

Model: 5.3 Chevy PU Fault Code: P0171 Posted: 2007-05-04 20:56

I own a 2000 Chevrolet C/K1500 with the 5.3L V8 engine. After recently replacing the rear knock sensor due to a mechanical issue, I've now developed a P0171 diagnostic code indicating a lean fuel condition in the left bank. This code did not appear prior to the service. I'm concerned that the repair might have affected the intake manifold gasket or related components. Since the replacement required removing the intake manifold, I suspect this could be linked to improper reassembly—such as a missing vacuum line or misaligned intake bolts. However, I'd like to understand whether there are other potential causes beyond mechanical assembly errors. Can anyone recommend specific steps or areas to inspect when troubleshooting P0171 on a 5.3L Chevy engine?

Related fault codes
P0171
Comments (4)
Anonymous 2007-05-05 06:01

If the truck was recently serviced and the P0171 code appeared after that, it's highly likely related to the intake manifold work. Since the knock sensor replacement required removing the intake, improper reassembly—like a missing vacuum line or loose bolts—is a common cause of lean conditions in 5.3L Chevrolet engines.

Anonymous 2007-05-05 09:00

This is exactly my situation—I bought the truck from a small dealership and had serious doubts about their mechanic's skills during the first service. I'm trying to diagnose the issue myself before returning to that shop, especially since the intake removal was part of the work. While it's likely tied to the repair, there could be other contributing factors like fuel system leaks or sensor malfunctions.

Anonymous 2007-05-05 10:58

It's not fair to spend your own time and money on troubleshooting without first getting a clear response from the service provider. If they won't assist, consider seeking an independent diagnosis.

Anonymous 2007-05-06 20:08

I investigated further yesterday and discovered a vacuum hose that had been left disconnected. I also found that the intake manifold bolts were not torqued to specifications. After reattaching the vacuum line and tightening all bolts according to factory torque values, the P0171 code cleared and engine performance has returned to normal. This confirms that mechanical assembly errors are a primary cause of this issue in 5.3L Chevy trucks.