Originally Posted by frdtruc1

To Matt and others who responded re low gas mileage. I am changing the 02 sensor. This based on putting the engine on a scope. Too old of a truck to have comp codes read. Result, needs new 02 sensor. Everything else checks out. I did put smaller tires on last week and have not driven it to determine if mileage affected. Will probably check that later this week. Hard to believe just changing the 02 sensor is enough to make a diff. but I'll let you guys know. Will be a while but will respond.