ok so i have a 1991 honda civic with a d15b2 my check engine light is on and im unsure y the car runs amazing after sitting for few hours it has a lil trouble starting in morning other than that nothing the car has a brand new timing belt plugs cap wires rotor intake manifold gasket and exhaust gaskets any ideas on y my check engine light is on or how i can test it since it is obd0 and no scan tool is made for obd0 any help would help thanks

 

You check those by watching the LED on the ECU. Pull down the carpet on the inside of the firewall where the passenger's feet would be. There is a red LED behind a small plastic window there. Turn the key on, but you don't have to start the engine. The LED will blink a number of times, pause, and repeat. Count the number of blinks in each group.