i have a 1999 civic EX 2-door auto.
a yellow check engine light came on. i did the paperclip thing to get the codes
i received 9 long flashes followed by a blank pause and then the same 9 long flashes ( this pattern keeps repeating till i remove the paper clip)

i did a search but the posts say that code 9(cylinder sensor-CYP) does not apply to models after 1998 . im having a hard time finding codes for 1999 and up vehicles
i recently changed my spark plugs, spark plug wires, distributor cap , rotor.(about a week and 1/2 ago), it might be relevant because i read that this is a distributor code

 

9 long flashes = 90, not 9. long = 10, short = 1.

from what i found... code 90 = "Evaporative Emission Control System leak detected in the fuel tank area"

this may be different on a 99, but it was listed for a 98

 

i have recently been smelling gas whenever i filled up my gas tank(either full or half). how can i fix this?

 

wow... umm.... that's a thinker. do you have a shop manual of some kind? if so, it may explain how to check it for a leak. i have no idea. i hope someone can give you a better idea than me. maybe try this. remove the rear seats. check around where the top of the fuel pump is located. perhaps look for a leak. maybe get the car on a lift and check under and all around the tank for leaks or holes or w/e. maybe someone else will have another idea.

 

New gas tank cap?

 

Thank God.....I was hoping the poor guy wouldn't have to pull his car apart before he checked the most basic problem. Just make sure that your gas cap is going on properly. If you've never removed or opened the panel going to the fuel pump assembly, I don't see why a leak would occur in that area.