high fuel consumption

What causes high fuel consumption ?

Hi. Welcome to the forum.

1) Mechanical or electronic problem
2)Lead foot!
Driving style and conditions contributes most to high fuel consumption. Particularly if the car seems to run fine otherwise. Inner city, bumper-to-bumper traffic really kills fuel economy.
Generally speaking you will get some other symptom(s) if there is a problem with the car. Like; it's sluggish, hard to start, poor throttle response, cuts out randomly, plugs get fowled, funny smells, squealing, excessive brake dust and so on.
If the engine is consuming more fuel than it needs, it just wont run well! If it needs to use that amount of fuel then there is something else wrong with the car or it's external factors, like driving conditions.