Hi everyone, I recently purchased a 98 Sidekick, it came with the automatic transmission and 4 wheel drive. I think it is a 1.8 engine. Love the care so far but seller had to clear the following OBDC code: P0740. He told me it has something to do with the transmission converter locking out/or not in high gear? He cleared the code and drove it around so he could get it smogged per California emissions. It passed smog check, he told me that once I drove the car over 53mph the check engine light would come on again, and sure enough it has.

I was hoping someone out there has had some experience with this code? The Seller said it was some kind of sensor/solenoid in the transmission that was sticking but it really would not effect the performance of the trans?

thanks, Dana - I appreciate the forum.
1998 Sidekick, 92,000 mi

I believe a P0740 is a "torque converter clutch circuit malfunction" - I can confirm this when I get to a manual later.

Note the words "circuit malfunction" - it suggests that the transmission controller is sensing a problem with the circuit.

The torque converter is what couples the transmission to the engine to allow power to be transmitted, the torque converter slips during normal operation and that "wastes" power and generates heat, under certain operating conditions, notably when the vehicle is at cruise speeds, the torque converter clutch locks the torque converter so that it does not slip, allowing for better fuel efficiency, and because it no longer slips & generates heat, longer transmission life.

The actual problem could range from a simple broken wire to a defective solenoid.