Having trans problem & got code P1790 with P0731. I believe I have to replace the output & input speed sensor. Anything else I may have missed here?
Those two codes together indicate an internal transmission problem. Most likely a problem in either the 2-4 clutch or possibly the underdrive clutch. A speed sensor failure normally has a speed sensor fault code along with multiple gear ratio codes. You dont have this. Let a trans shop check it to be sure.
Transman618 Is A Transmission Repair Professional.
His Advice Describes Am Experience I Had With A Chrysler 2.7L/Automatic.
The car was shifting improperly. The codes I had were:
PO700 - Trans Control Malfunction
PO715 - Input / Turbine Speed Sensor A Circuit Malfunction
PO731 - Gear Ratio Incorrect 1st Gear
PO733 - Gear Ratio Incorrect 3rd Gear
PO734 - Gear Ratio Incorrect 4th Gear
Note : As an experiment, I tried resisting the advice to always replace the input and output speed sensors as a pair. I put in just the input sensor and it fixed the transmission very temporarily. Although I had no code for an output speed sensor, I found that replacing the output sensor after that fixed everything for good. These little plastic sensors are not very expensive.
I would follow Transman’s advice and have it checked by a professional.