2002 GM 5.3L Tahoe P0171 and P0174 Fault: Fix with Intake Manifold Gasket Replacement

I was experiencing recurring P0171 and P0174 engine diagnostic codes on my 2002 GMC Tahoe with a 5.3L V8 engine. After replacing all four oxygen sensors, the issue persisted. Through research in various forums, I discovered that many 2002 GM 5.3L Tahoe owners face a common problem: leaking intake manifold gaskets allowing excess air into the combustion chamber. This causes misfires and incorrect air-fuel ratios, triggering the P0171 (rich mixture bank 1) and P0174 (rich mixture bank 2) codes. The fix is relatively simple—replacing the intake manifold gasket—which costs around $30 at a local auto parts store like NAPA and takes approximately 3 hours to complete on a Saturday. The main challenge during disassembly is disconnecting the fuel injectors. To do so, you must squeeze the black tabs inward, slide the gray locking tab outward, press the top of the gray lock, and then pull the connector off. This process requires careful handling but is manageable with patience. I successfully resolved the issue using this method. Located in Denver, CO.