Gas cap
it means you need to check the engine
This means that something may be wrong with your engine. Take it in to a mechanic and get everything checked out.
Flashing check engine lights means one or more cylinders are misfiring. Could be injectors, coils, plugs, wires, etc. Get it to a shop.
The check engine code PO136 means the O2 sensor circuit malfunction
If you are referring to the Check Engine light, then it means that the computer has detected a problem with the emissions system. Have the computer scanned to get the code. This code will lead you in the direction of the problem.
The 1991 Toyota Corolla does not have a zero-clearance engine. It has a non-interference engine. This means that the pistons will not travel to the pistons.
The check engine light could any number of things. It is impossible to know what the light means without having the car checked by a mechanic. The mechanic will then be able to tell what is wrong with the car.
Trouble code P0174 means: System too lean (Bank 2)
It means that you have problems with your engine. It can be the oxygen detector or another malfunction. To make the story short you have to visit your mechanic. Or if you have an error code reader youcan check error codes and figure out what to do next.
Trouble code P0446 means: Evaporative Emission System Vent Control Circuit
I think it means you need to check your engine.
light means there is a fault picked up by ecu.error code must be retrieved and analised.Once repaired the light will go off.