The 2019 Chevrolet Malibu features 4-cylinder engines—the 1.5L turbo or 2.0L turbo depending on trim. Both are inline-4 configurations with only cylinders 1 through 4. When P0306: Cylinder 6 Misfire Detected displays, you're facing an anomalous code.
Four-Cylinder Sedan
The current-generation Malibu (2016+) has always been 4-cylinder only. Previous generations offered V6 options, but if your 2019 shows P0306, it cannot represent an actual cylinder 6 misfire since that cylinder doesn't exist.
Causes of Erroneous P0306
At this vehicle age, OBD-II port corrosion may affect data transmission. Scanner interpretation issues with GM protocols cause false codes. Aftermarket devices may interfere with diagnostics. Generic scanners designed for older V6 Malibus may misinterpret data.
Diagnostic Protocol
Clear all codes and monitor for recurrence. Use GM GDS or professional equipment for accurate readings. Inspect and clean the OBD-II port if needed. Remove aftermarket devices temporarily. Check for legitimate misfire codes (P0301-P0304) if drivability concerns exist.
Older Vehicle Considerations
At this vehicle age, port cleaning may resolve communication issues. If actual drivability problems exist, focus on valid diagnostic codes rather than the impossible cylinder 6 reference.