If your 1999 Toyota Sienna runs fine but you are getting 100-125 miles less per tank of gas is this an oxygen sensor or EGR valve problem?

Answer 1

1 dirty or cloggedair filter element . 2 Low tire presure , or incorrect tire size. 3 dirty or clogged fuel jets. 4 emissions system not funtioning properly .

If the egr or O2 sensor were a problem, the check engine light would be on. Many factors affect fuel consumption including Tune up parts such as plugs, fuel filter or air filter. Cleaning the throttle bore and intake valves can also have an effect. At some non-regulated gas stations such as reservations may not be giving you a full gallon even though the pump gauge says it is. As mentioned above tire pressure is a factor. Anything that is putting a drag on the movement of the vehicle such as a dragging brake will hurt miliage. Driving habits will greatly change miliage. Addition weight such as a truck cap or additional passenger, added on will hurt miliage. Davey@buffalo.com

Check for vacuum leaks, PCV leakage. There is also possibility of winter running conditions that usually run less miles per tank. Some tyres have better grip with less mileage per gallon.