A week ago I take my truck mudding for the first time sense I got it, it goes fine till I hit a huge puddle and it dies. Has issues starting at first then goes just fine. 10 minutes later engine light comes on. Auto-zone said it was my o2 sensor. Its not hooked to my exhaust (it was dangling under the truck) so yea it was wet. They cleared it so the next day I put the sensor back on the exhause and went to the mud again. The truck dies and its even harder to start, But no codes came up or anything. Today I took it to the car wash to clean it, after I get done I couldn't start the truck till after about 10 attempts. Once the truck starts there is no problem.
I'm guessing something is getting wet and shutting the truck off but I don't know what it is, any ideas?

 

I'm not saying with certainty that this is it, but a hairline crack in a distributor cap will do that every damn time. A really old dry-rotted coil high voltage lead (center terminal on cap) will, too.

The oxygen sensor surely isn't at fault, since the truck starts in open loop anyway.

 

How deep was the water you were going through? I'd check the air intake to see if maybe you sucked some crap into there... Distributor would make sense too.

 

The water was about a foot deep. Ill take the distributor off tomorrow and see how it looks. I planned on changing it anyway with my plugs and wires after I fixed the plenum, I might have to do it before.