A 2001 Buick Century Custom came to a transmission shop with a complaint of jerky shifts. A road test of the vehicle showed that all shifts were harsh, and a scan check registered the generic gear-ratio-error code P0730. Since code P0730 does not illuminate the malfunction-indicator light, the harsh shift was the customer’s only clue that anything was wrong.
Three to six months after you overhaul a 4T65-E transaxle, the vehicle may come back with a code, either P0730 (incorrect/undefined gear ratio) or P1811 (maximum adapt and long shift).
Generally, code P0730 occurs immediately after installation of a transaxle with an incorrect ratio. This could mean that either an exchange unit with an incorrect ratio was installed or incorrect sprockets and/or final drive was used during rebuild in the shop.