this is a 98 cr-v. this is what has happened/been done to the vehicle recently:
removed and re-installed header (possibly damaged o2 sensor? o2 sensors have their own codes though)
ran out of gas on a highway - refueled with 92 gas and started driving worse for some reason - started feeling better right after adding 87 gas.

what could this be?

 

i believe 67 is the code that your polluting more than tolerable levels. I had that code thrown when I had a racing cat on my car. Its not going to kill you. Just reset your ecu, and see if it comes back on again. If it does you either have a bad o2, or your cat is not working anymore.

 

how do you reset the ecu?

 

take out the 15amp ecu fues under the hood out for 15 mins

 

i thought it was the 15 and the 7.5 next to it? anyways, that's what i did, and the code hasn't come back yet.