My check engine light came on and I retrieved the code P0770. What does it mean? Is it safe to drive with this problem?
What is the make, model, mileage?
Does the transmission shift normally and does the vehicle drive ok? It’s probably a sticking solenoid or something in that area. I would get it looked at by an independent transmission specialist in any regard. It could be a minor problem but it’s always better to be safe than sorry.
Make/model/year of vehicle would help.
That generic code is for a problem with the lock-up torque converter (TC) in the automatic transmission. It is supposed to lock above certain speeds to improve gas mileage. Apparently yours isn’t do that.
It’s a '99 corolla
Is the check engine light on steady, or is it flashing?
Steady.
I’m guessing this is a problem that doesn’t have to be fixed urgently?
I think that’s a good guess. If I had this problem I’d see if I could get some advice on the urgency by phoning the local Toyota dealership shop. They’ve probably seen this problem before.
There used to be a guy on this forum that called himself “Transman”, a transmission specialist and a really good and knowledgeable guy. He steadfastly maintained that if the torque converter’s lock-up clutch was left unplugged so that it didn’t engage ( or couldn’t engage in your case) the transmission would overheat.
He knew his stuff, and saved a lot of people a LOT of money. I’d believe him.
That could well be the case, if only by the laws of physics. If the TC allows slip between the flywheel and the transmission input shaft, there’s fluid being pushed around inside the TC under pressure, and that will cause friction and heat. Once the lock occurs, that source of heat mostly ends.