What make an engine run hot in only one cylinder?

Thanks for your response. The information on OBD-ll code is new to me I will recheck that. the reason for one cylinder running hot is just a feel. It looks like the heat off the engine is more pronounced to the rear of the engine (#7 cylinder). The temp. gauge reads normal along with oil pres. I am going to borrow an infrared eat gun to see more accurately. Could the rear main bearing? and if so is there any way to check without pulling oil pan?