DTC P0301-P0306: Cylinder Misfire Detected: Description
WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) uses information from the Crankshaft Position (CKP) sensor and Camshaft Position (CMP) sensor in order to determine when an engine misfire is occurring. By monitoring variations in the crankshaft rotation speed for each cylinder, the PCM is able to detect individual misfire events. A misfire rate that is high enough can cause the Three-Way Catalytic Converter (TWC) to overheat under certain driving conditions. The Malfunction Indicator Light (MIL) will flash ON and OFF when the conditions for TWC overheating are present. If PCM detects a misfire rate sufficient to cause emission levels to exceed mandated standards, DTC will set.