Why Is My Car Using So Much Gas?

If your vehicle is using more fuel than usual, something may be affecting engine efficiency.

Fuel economy can drop because of low tire pressure, driving conditions, overdue maintenance, worn spark plugs, dirty filters, sensor problems, fuel-system concerns, or mechanical issues.

A small change may be normal, but a sudden or continuing drop should be inspected.

Common Causes of Poor Gas Mileage

Low Tire Pressure

Underinflated tires create more rolling resistance, which makes the engine work harder.

Check tire pressure using the recommended PSI listed on the driver-side door label.

Also inspect the tires if the pressure warning light keeps returning after adding air.

Worn Spark Plugs

Spark plugs ignite the air-and-fuel mixture inside the engine.

Worn or contaminated spark plugs can cause incomplete combustion, misfires, rough idle, hesitation, and reduced fuel economy.

Dirty Engine Air Filter

The engine needs clean airflow to operate efficiently.

A heavily restricted air filter may reduce performance and contribute to poor fuel economy, especially when combined with other engine problems.

Oxygen Sensor Problem

Oxygen sensors help the engine computer control the fuel mixture.

A failing sensor may cause the engine to use too much fuel. Warning signs may include:

• Check-engine light
• Poor gas mileage
• Rough idle
• Failed emissions test
• Weak acceleration
• Strong exhaust smell

Dirty or Leaking Fuel Injectors

Fuel injectors deliver fuel into the engine.

Dirty injectors may not spray correctly, while leaking injectors may deliver excess fuel. Either issue can affect performance and efficiency.

Mass Airflow Sensor Problem

The mass airflow sensor measures air entering the engine.

Incorrect readings can affect the air-and-fuel mixture, causing hesitation, rough running, power loss, or increased fuel use.

Sticking Brakes

A sticking brake caliper can make one wheel drag while driving.

This creates resistance and may cause poor fuel economy, heat near a wheel, uneven brake wear, pulling, or a burning smell.

Alignment or Tire Problems

Poor wheel alignment, damaged tires, or uneven tread wear can increase rolling resistance.

If the vehicle also pulls to one side or the tires wear unevenly, schedule a tire and alignment inspection.

Driving Conditions Also Matter

Fuel economy may temporarily decrease because of:

• Heavy traffic
• Short trips
• Aggressive acceleration
• Excessive idling
• Carrying heavy cargo
• Using air conditioning frequently
• Driving uphill
• Colder weather
• Roof racks or external accessories

However, driving conditions do not explain every sudden fuel-economy drop.

Warning Signs That Need Diagnostics

Schedule an inspection if poor gas mileage happens with:

• Check-engine light
• Rough idle
• Engine misfire
• Fuel smell
• Black exhaust smoke
• Weak acceleration
• Hard starting
• Engine stalling
• Tire pressure problems
• Brake dragging
• Fluid leaks

A fuel smell, black smoke, or flashing check-engine light should be addressed quickly.

Why Diagnostics Matter

Replacing random maintenance parts may not fix poor fuel economy.

A proper inspection may include:

• Scanning engine trouble codes
• Reviewing live sensor data
• Checking tire pressure
• Inspecting tire wear and alignment
• Checking spark plugs and ignition coils
• Inspecting the air filter and intake
• Testing oxygen and airflow sensors
• Checking fuel injectors and fuel pressure
• Inspecting brakes for drag
• Looking for fuel or vacuum leaks

This helps identify the actual cause before repair work begins.

How OWL-LET May Help

OWL-LET provides diagnostics, maintenance, and auto-repair services for San Diego drivers.

Depending on the selected membership plan, members may receive free diagnostics, qualifying parts at cost, member labor pricing, and roadside benefits. The Personal Plan starts at $24.99 per month.

If your fuel economy has suddenly dropped, OWL-LET can inspect the engine, ignition system, sensors, fuel system, tires, alignment, and brakes before recommending repairs.

Schedule Fuel-Economy Diagnostics in San Diego

Do not keep spending more at the gas pump without identifying the cause.

OWL-LET Service Center
1739 Palm Ave, San Diego, CA 92154

Phone
+1 (619) 777-0031

OWL-LET can help diagnose poor gas mileage, warning lights, misfires, fuel-system problems, tire concerns, and brake drag.

Service availability, diagnostics, repair pricing, parts, and membership benefits vary by vehicle and selected plan.