Frigidaire gas range fault codes F99 and dr

Our frigidaire gas range had a fault code of F13. We replaced the clock/timer (electronic oven control). We were able to set the clock and the controls seemed to be working. The first time we tried the oven however, we received a F99 code and dr code. The oven does not work. I can clear the fault codes and use the cook top but not the oven. Does anyone have any suggestions? Thank you - John