PO151 and PO131 Diagnostic for 1999 Chevrolet Suburban K1500 - Fuel Pump Replacement & O2 Sensor Issues
I own a 1999 Chevrolet Suburban K15-00. After replacing the fuel pump in April, the vehicle initially ran smoothly. However, I began experiencing a loss of compression when driving uphill after only a short period of use. I replaced the air filter and subsequently performed a fuel filter change and injector cleaning. I later learned that some 1999 GM trucks require a new wiring harness for the fuel pump due to connector degradation—however, the connector on the replacement harness I purchased does not match the original. After months of inconsistent driving, the check engine light activated, displaying diagnostic codes PO151 and PO131. Given that this is a common issue in older GM trucks, I'm seeking advice on how to properly diagnose and resolve these codes without further damage.
The fuel pump connector you're referring to is located at the pump itself. On many GM vehicles, when the fuel pump fails or operates under poor conditions, the connector can melt and degrade, leading to intermittent voltage drops and poor electrical contact—this often results in recurring fuel pressure issues even after replacement. While this issue may not directly cause PO151 and PO131 codes, it's worth checking. These codes are more commonly associated with oxygen sensor malfunctions or a restricted catalytic converter. It's very typical for older GM trucks to develop clogged catalytic converters that trigger O2 sensor-related error codes. I hope this helps—please keep us updated on your progress.