My question is about code 23 what posible sorces sould i look for to remidy this code. I have a 91 305 tbi engine. I found my air temp sensor to be on the exaust manifold and slightly melted, i cleaned it up and reset the code. the check engine light used to come on under exeleration after driving for about an hour, now it will pop up on idle after me relocating the sensor. I have a new sensor odered from gm but do u guys think i should check anything else, the tip with the two wires on the sensor are still intaced, so besides the sensor do u guys think i sould look for any other posible sorces of this code and if so what sould i check out. thanks guys