1998 Mitsubitchi Galant!!! Check engine light is on. What do I do next? Code P0170?
It has been well maintained and everything works. Drives fine but check engine light is on. Original code was P0170-Fuel Trim Malfunction. I replaced the gas cap and added B-12 to the gas tank to clean the fuel system and injectors, erased the codes and drove to reset the computer. At 67 miles, check engine light came back on. New code is P0125-Insufficient Coolant Temp for Closed Loop Fuel Ctrl. I replaced the thermostat with an OEM part from the dealership and erased the code. Drove about 20 miles and the code P0170 comes back. What should I do next? and if that doesn't work, what then? and so on.
Any help would be appreciated.