2000 GMC Sierra Z71 5.3L Engine Fault Codes P0161 and P0300 - Rough Idle and Exhaust Air Inflow
My 2000 GMC Sierra Z71 with a 5.3L V8 engine is experiencing a rough idle and starts with a noticeably shaky performance. I've also noticed that the exhaust appears to be pulling in air, especially in the morning. There's no loss of power or acceleration issues, but the symptoms are concerning. The check engine light has triggered fault codes P0161 and P0300. I'm looking for advice on how to diagnose and fix these issues without major repairs at this stage.
P0161 - B2S2 O2 Sensor Heater Circuit: Check if there is 12V at the pink wire of the sensor, ensure the black wire has a solid ground connection, and measure the resistance in the heater portion of the sensor. P0300 indicates a multi-cylinder misfire; given cooler temperatures, it's worth checking fuel pressure as this could be contributing to the issue.