my car have a po 770 check engine light on what could be

P0770 TOYOTA - Shift Solenoid 'E' Malfunction -- Low transmission fluid level - Dirty transmission fluid - Faulty shift solenoid 'E' valve - Shift solenoid 'E' valve harness is open or shorted - Shift solenoid 'E' valve circuit poor electrical connection

The ECM uses the signals from the Throttle Position Sensor and Air flow Meter to monitor the engagement condition of the lock up clutch. Then the ECM compares the engagement condition of the lock up clutch with the lock up schedule in the ECM memory to detect mechanical trouble of the shift solenoid valve SLU, valve body, torque converter clutch and automatic transmission assembly

This is the code I got on my 95 avalon with 200,000 miles, 2 yrs ago. The O/D light flashes slowly and the car does not shift to highest gear for the first 3 minutes (until the tranny warms up?) of driving, then it shifts fine. A tranny shop told me that it probably would keep going indefinitely. I saw another owner on another site who had the code for 4 yrs and 55,000 miles without further problems. It's not completely normal, but expensive to dig into a transmission to replace the solenoid or the connection.