You either have a bad valve body/solenoid in the transmission or the reaction sun shell in the transmission has failed.It may be best to have a transmission shop look at it or the dealer if you don't feel comfortable with transmission work. A scan tool would be required to diagnose the condition completely but those would be the two top choices if I were checking it in person.If you choose to attempt the repair I will try to help as much as possible.
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Master ASE Certified.L1 Advanced Engine Performance Certified.Pa Emission Repair Technician.Just Answer Car Category Mentor.
