P1870 Error Code

I received the error code P1870 on my '96 Cutlass Supreme SL. i was wondering what the code meant because i cant find anything on the internet about it. The mechanic said it was something with the TCC slipping. quote to get it fixed would be around $500. any information would be helpful. Thanks, Ben

Take the car to a tranny shop and have it diagnosed. Most shops just throw parts at problems but don't really fix them. This will show you what the code means: http://www.troublecodes.net/OBD2/Pcodes.shtml#1800

Most common is the tcc valve body bore wearing and when the tcc is applied a pressure loss occurs , the pcm sees this slippage and boosts pressure in an attempt to compensate. The VB can be repaired/modified to permanently correct this. A full trans scan should be done to confirm the problem.