99 GMC 2500 Pickup OBD2 Codes P0151, P0131, P0137, P0157 - Bogs on Uphill with Power Loss
Hi, I have a 1999 GMC 2500 pickup with a 5.7L engine and 104,500 miles. The vehicle shows OBD2 fault codes P0151, P0131, P0137, and P0157. It runs smoothly under normal conditions but begins to bog down and lose power when driving uphill. After reaching the top of the incline, performance returns to normal. Although these codes are related to oxygen sensors, I'm unsure whether all of them are faulty—could one sensor be causing the issue or is there another underlying cause?
I suspect a wiring issue might be responsible. First, verify that the O2 sensor fuses are not blown—check the fuse box for any damaged or missing fuses. Next, inspect the oxygen sensor wire harnesses for any signs of damage, such as fraying, short circuits, or physical breaks. If all these components appear intact, the issue may lie elsewhere—possibly related to fuel delivery. Please update with your findings so we can further diagnose the problem.