Q: Diagnostic code P0721

Hi....the best thing to do is request a diagnostic based on the trouble code, P0721, that you have in hand. Resolve that first as the fault behind the trouble code may account for the shift difficulty you are having. The potential faults that typically cause P0721 to set are limited in extent. The causes of P0721 include: a malfunctioning transmission fluid temperature sensor, a malfunctioning output shaft speed (OSS) sensor, a malfunctioning speed sensor, or problems with the electric wiring or connections to those components. Among the steps that a mechanic would take are removing the OSS sensor and inspecting its condition, especially its teeth and the sensor’s resistance, inspecting the wiring harness for loose connections or wires that have been damaged, and checking the power supply to the OSS sensor as well as the PCM harness. If you desire that this problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an automatic transmission shift diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.