Check this first
Check the transmission fluid level and condition first, and have the transmission module read.
What usually fixes it
In the order a good shop checks them. Typical total: $236–$4,800 at $130 an hour.
Fluid and filter service
$276–$644Old fluid causes many shift complaints.
Shift solenoid or sensor
$392–$988Electrical parts inside the transmission.
Internal transmission repair
$1,232–$4,800Clutches or the torque converter.
This is the advice for this family of codes – Drive DTC doesn't have advice written for P0712 on its own yet.
Code titles are the generic SAE definitions. Prices are typical US parts and labor for a common car or light truck – a guide for judging a quote, not a quote. Always confirm a repair against the vehicle in front of you.