My 1997 Legacy recently started throwing a P0740 (torque converter clutch system malfunction) code, but doesn't have any symptoms at all. Shifts fine through all gears including the top one. Never really have to rev the thing about 3000 rpm to cruise on the highway.

 

I've wiped the code, but it comes back again once I hit highway speed.

 

My plan for now is to ignore the situation.

 

Anyone think I should do something different?

Have only encountered this code two times.

A slightly bent dipstick was grounding out on the solenoid body when inserted. Replaced stick.

The tach was malfunctioning and the tcu couldn't gauge engine speed. Fixed ground issue on circuit board.

Others may have aid in this area.

 

O.