2000 GMC Sierra 5.3L Engine P0157, P0172, P0175, P0330 Fault - Oil Consumption & Knock Sensor Issue
My 2000 GMC Sierra with a 5.3L V8 engine has developed several diagnostic trouble codes after being mudded extensively a few months ago. Since then, the vehicle exhibits inconsistent idle behavior—engine RPMs drop frequently and it occasionally stalls when first started. A Superchips tuner revealed the following codes: P0157 (O2 Sensor 1 Bank 1 Signal Malfunction), P0172 (System Too Rich), P0175 (System Too Rich), and P0332 (Knock Sensor 2 Circuit Low Input - Bank 2).\n\nP0172 and P0175 both indicate a system running too rich, which I believe is due to mud contamination of the Mass Airflow (MAF) sensor during an intake cleaning. I have since ordered a replacement MAF sensor.\n\nThe P0332 code—indicating a low input signal from Knock Sensor 2 on Bank 2—is the most confusing. I am not familiar with this fault and do not know how to diagnose or repair it. I have basic mechanical skills and hope this is a straightforward fix.\n\nAdditionally, I've noticed significant oil consumption. I'm unsure whether this is caused by the rich fuel mixture or the P0332 code. Could the prolonged running rich lead to piston ring wear or oil washdown? Are there other potential causes such as an intake gasket leak?\n\nAny insights or troubleshooting steps would be greatly appreciated—thank you in advance!
Inspect the wiring harnesses connected to the oxygen sensors in the exhaust system. Mud and off-road use may have damaged these connections. Similarly, check for any physical damage to the knock sensor wiring or its mounting location. If the engine was submerged during mud operations, this could affect sensor functionality. Excessive oil consumption can occur when the engine runs too rich, as it may wash down piston rings due to high fuel volume. An intake gasket leak is also a possible cause—ensure all seals are intact and properly seated. Please provide updates if you find any issues or need further guidance.