The sportage was nearing empty (ie. the light was on) so I pulled into the gas station and filled it. 15 seconds or so after I pulled out of the gas station in began to sputter and backfire but didn't stall. I have driven it about 50 miles like this and the condition has not improved. While driving the Check Engine light flashes. I pulled the codes when I made it home and there were "Low voltage to Bank 1 sensor 2" and "Misfire on Cylinder 3" I have had the first code for quite a while. Do you think it is just bad gas, or do you think there is a more serious problem? FYI, the gas tank is brand new (less than 2 months) and the pump and filter were replaced at the same time. Any thoughts?

had it been raining or real cold ? some of the guy's here have used some type of water dryer in the tank. # 3 plug could have went bad, how long from the last tune up ?

Could also be the usual oil on the plug that just co-incidentally happened at the most confusing time.

Yes a bad plug could cause it, as could a bit of water, but the water would have to come through the injector and that would give similar results to a bad plug if fouled or blocked with water.

Low voltage bank 1 sensor 2 would be a blown heater fuse to one or both of the O2 sensors, could cause a "limp home" condition.

Where is the O2 heater fuse?

Thanks,
Chris

Should be engine bay fusebox...

Could be the connector also at the sensor (corrosion/salt/etc)

Will check the fuse. Thanks! When I clear the codes will it take the vehicle out of "limp mode" or is there another process to do that?

Thanks!

Clear the codes and it should be out of "limp home" (open loop mode = same as start-up/warm-up)

Well all the fuses were ok, I cleared the codes and it's still running awful. I had about 3 gallons used so I put some fuel stabilizer in and topped it off with 3 gallons of premium (no ethanol) gas. Any other suggesting before I start taking stuff off to look at the plugs?

Check/replace the fuel filter, and run some injector cleaner through it. I think you could have got down to the dirt in the tank, sloshed it around with new gas and clogged the filter. If it was ok when you drove in to the pumps and not ok when you drove out it is most likely something with the gas. I had the same problem a few years back, ok before fill up, spitting sputtering and running bad after the fill up. I had several codes also. I spent about $500.00 on parts chasing codes and by accident fould the clogged filter. Changed it out and all was well.

Hope this helps, Dennis

Have you replaced the plug wires lately? Mine started doing that and it was a plugged catalytic converter. I drilled out the honeycomb on the pre cat and replaced the plugs and plug wires. It ran fine for a while then started missing and backfiring and it came up with a misfire code. I replaced the coil pack and it is running great now.
I also did some modification on the O2 sensor so it would not throw a code and that seems to be working. I bought two used coil packs on line for $32 including shipping so now I have a spare.