If you notice your car has bad gas mileage or poorer gas mileage than it used to, there are a number of parts on your car that can affect it negatively. Find out what causes bad gas mileage and how to diagnose and fix these parts yourself with our how-to videos.
Parts in Your Car That Can Cause Bad Gas Mileage
These parts in your car could cause bad gas mileage and are listed in no particular order.
1. Brakes
Binding brakes can make your car or truck work harder. You may have a brake caliper or brake caliper bracket, brake shoes or brake pads, or a brake cable that’s binding up.
2. Vacuum Leak
A vacuum leak can affect the air-to-fuel ratio and cause your engine to dump more fuel than it needs to.
3. Throttle Body
Carbon can build up on the throttle body and affect airflow, causing weak acceleration and possibly engine stalling while driving.
4. Catalytic Converter
If your engine isn’t working efficiently and dumping excess fuel into the catalytic converter, that can damage the converter and affect fuel mileage.
5. Fuel Pump
A weak fuel pump can waste gas and cause worse acceleration and power, and it might not turn on a check engine light.
6. Cooling Fans
Weak cooling fans can cause the engine to run hotter. This will cause the computer to dump more fuel into the engine, giving you bad gas mileage.
7. Air Intake System
Parts of the air intake system like the engine air filter, mass air flow (MAF) sensor, throttle body, and intake manifold can leak too much air into the system, causing the computer to waste more fuel than necessary in response.
8. Suspension Parts
Suspension parts can cause bad gas mileage without turning on the check engine light. Worn suspension parts can wear the tire tread and affect how straight your car drives. Bushings can wear out and shift the differential, creating resistance.
9. Spark Plugs, Ignition Coils, and Spark Plug Wires
Bad spark plugs and ignition coils can reduce engine power. Problems like moisture getting inside or corrosion can cause problems with fuel mileage.
10. Oxygen (O2) Sensors
Damaged or faulty O2 sensors can send a false reading to the car’s computer, and this can cause it to dump more fuel into the engine’s combustion chamber and waste gas.
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