Good morning. My sons 1998 S70 had this code this morning. We repalced his transmission in March 2013 with a low mileage unit out of a wreck. Everything had been working great until last night when he said it began slipping. After sitting for awhile it ran agin for about 5 miles before it started slipping again, and the arrow on the dash is flashing and the lights for the S,W,E on the shifter are flashing. Any input? My OBD reader indicates PO734,
Error 4 gear ratio. Fluid is full and clear.