One of the most important contributors to the fuel management system on a fuel injected vehicle is the coolant temperature sensor. You could almost look at this sensor like the vehicle’s “choke” that a carbureted engine uses. Engine temperature dictates when many things happen with your engine management system. If there’s a problem with the cooling system, it can have a direct effect on fuel economy and engine performance.
Now before you get all happy and replace your coolant temp sensor, think basic. Remember I said not to make things complicated. Try two things. First, make sure your cooling system doesn’t have any air in it. Here’s a video on how to do that. More info can be found in the What to Do If Your Engine Overheats article.
If you’re sure there’s no air in your cooling system and you still suspect a problem, you might check the thermostat. If your vehicle is equipped with a temperature gauge and you notice that it doesn’t come up to temperature like it should, you might consider replacing the thermostat. Your engine is designed to get up to operating temperature quickly so that it runs as efficiently as possible. If it doesn’t get up to temperature quickly and efficiently, your MPG will suffer. Aside from that, thermostats are wear items; they are mechanical devices that will eventually fail. So if you start to notice an issue with one, replace it sooner rather that later to ensure efficient engine operation.