Hi all this is my first post and am hoping for some sound advice on how to fix my issue. I have a 2008 Civic EX 4-Dr. Long story short but yesterday I mistakenly put nearly 2 gallons of water in my fuel tank. I left home and about 1/4 down the road it stalls and suddenly I realized the gas container I used had water in it. So my brother and I push the car back home and I did some research on this site. I removed the rear seat to get at the top of the tank siphoned out the entire tank and put 3-4 gallons of fresh fuel in. Cranked the starter for about 2 minutes and it finally started. Idles fine but when you go to give it gas it will hesitate and the check engine light is flashing. I let it idle for a good hour but no change. I'm in the process of getting a code reader but in the meantime...is there only a fuel filter inside the tank and not an inline one?...and I'm thinking the water was flushed through the lines being that the car eventually started so should be good there? Any advice would be great thanks!

 

O2 sensors in the exhaust system might be fried. I would check the codes and deal with it then.

 

Your main fuel filter is like a half cup and must also be changed. Water is not as nearly thin as fuel and when it hits the pintle inside the fuel injector it's like a milkshake flowing through a coffee straw. It will finally purge itself if it gets suspended in the fuel with some methanol (HEET) but will not run fine for a while unless the system is opened and blown out from tank to rail.
Sucks to have water in fuel. O2 sensors will not get hurt at all by water vapor. Heck people routinely inject water into their turbo motors to control detonation.