Honda Car Forum

The car started having problems all of sudden in the morning. Replaced spark plugs, spark plugs cables, oxygen sensors, etc etc. and still giving problems + 4 error codes ( non related with the main issue ). So I decided to replace the ECU. After replaced the car won't start because the key light keeps blinking. The mechanic told me that he need to reset the ECU to put my key code so it can start. The question is where I can get this code? according to the owners manual there is Key Number Plate but this is a pre-owned car so I don't have that info. Someone told me to check for a sticker in the glove compartment but it wasn't there. any other suggestions? Thanks.