Poor fuel economy
A sudden drop in fuel economy usually has a mechanical cause; a gradual drop can simply be driving conditions, season or tires.
AreaEngine
UrgencyLow
Can I keep driving? Safe to drive short-term, but have it checked to avoid failed emissions or worse fuel economy.
Common causes
Low tire pressure
Increases rolling resistance.
Thermostat stuck open
The engine runs cold and rich.
Faulty oxygen sensor or MAF
Incorrect mixture.
Dragging brake
A sticking caliper.
Clogged air filter (older engines)
Has more effect on carburetted and older engines.
Winter fuel, cold weather, short trips
Normal seasonal changes.
What to check
- Check tire pressures.
- Read fault codes.
- Check the temperature gauge reaches normal.
- Compare with the EPA figures for your car in our car database.
Related OBD2 codes
Repair guides
Other engine problems
General guidance only. A qualified technician can confirm the cause; brakes, steering and fuel leaks should be checked professionally if in doubt.