Honda Civic Si Problem Report
Honda Civic Si Harsh Shifting of Automatic Transmission
The shift control solenoid externally mounted on the automatic transmission can fail and causes a harsh 1-2 shift. Replacing the shift solenoid and flushing the transmission with genuine Honda automatic transmission fluid may eliminate harsh shifting characteristics. A broken internal spring can cause the same issue. If the shift control solenoid does not repair the problem, the transmission will have to be replaced.